This session was presented by David Intersimone as part of Embarcadero’s CodeRage 2018 virtual developers conference. The conversation took place live online on December 4, 2018.
Bjarne Stroustrup (designer and original implementer of C++, Managing Director in the technology division of Morgan Stanley in New York City and a Visiting Professor in Computer Science at Columbia University) participated in a C++ conversation with David Intersimone “David I” (Embarcadero MVP). Bjarne recently attended the ISO C++ committee meeting in San Diego where committee members continued work on the next International Standard (IS), C++20.
This CodeRage conversation covered some of the recent language proposals as well as other important C++ features that will be included in the future. Specific C++ areas David asked about included the future of generic programming (Concepts), how to better organize C++ code (Modules), and how to ensure stability in the language while also allowing the language to evolve.
Some C++ developers also use Python for their application development. There are several ways to integrate the two languages together. One way is to create Python extension modules containing C++ functions that implement new object types and functions. Another way is to use the Boost Python C++ library that enables interoperability between the Python and C++ languages. A third way is to use the productivity, resusability, and encapsulation of components to to integrate C++Builder and Python. In this chapter you’ll learn how to use the Python4Delphi open source components in your VCL applications.
Introduction to Python4Delphi (and C++Builder)
Python for Delphi (P4D) is a set of free components (MIT Open Source License), created by Kiriakos Vlahos author of the popular PyScripter Python IDE, that wrap up the Python DLL into Delphi. The components allow you to create or extend your Delphi and C++Builder applications to execute Python scripts, create new Python modules and new Python types. You can also create Python extensions as DLLs and much more.
You’ll find Python4Delphi on GitHub at https://github.com/pyscripter/python4delphi. The GitHub project includes a readme file, installation notes, supported platforms, how Python4Delphi finds your Python distributions, tutorials and demos.
Jim McKeeth recently hosted a webinar with Kiriakos, “Python for Delphi Developers Part 1 – Introduction” (replay is available on YouTube). A Part 2 Python for Delphi Developers will take place on Wednesday, October 14, 2020 at 7am Pacific Time. While this webinar series focuses on Delphi programming, it also provides information about the Python4Delphi components and Python programming that can help C++Builder developers.
While the webinar and Python4Delphi speaks to Delphi developers, C++Builder developers can compile and install the components for use in their Win32 and Win64 C++ VCL applications. To build and install the Python4Delphi components you can use all editions of C++Builder (community, professional, enterprise and architect) and RAD Studio (professional, enterprise and architect) for versions 10.3.3, 10.4 and 10.4.1. If you only have C++Builder, you’ll learn how to use the included Delphi DCC32 and DCC64 command line compilers to build the Delphi component package project and install the components.
Installing Python for Windows (32 and 64 bit)
Before you start using the Python4Delphi components in your C++Builder VCL applications you’ll need to make sure you have Python for Win32 and Win64 installed on your computer.
To find Python distributions installed on your computer, use the “where python.exe” Windows command.
By default, Python for Win32 installs into the C:\Users\david\AppData\Local\Programs\Python\Python39-32\ folder (or wherever you tell the install to put the distribution).
By default, Python for Win64 installs into the C:\Users\david\AppData\Local\Programs\Python\Python39\ folder (or wherever you tell the install to put the distribution).
Installing Python4Delphi and Using the Components
The following are the steps I followed to download and build the Python4Delphi components for use with C++Builder 10.3.3, 10.4 and 10.4.1. While I used RAD Studio (which includes C++Builder and Delphi), you can also use C++Builder along with the Delphi command line compilers to compile and install the components.
Step 1 – Download the latest release of the Python4Delphi
Grab the python4delphi-master.zip file (https://github.com/pyscripter/python4delphi) and unzip it to your hard drive (I put it in my C:\Users\david\Documents\Embarcadero\Studio\Projects/ folder).
Step 2 – In the IDE open the Python_D package project file (RAD Studio editions)
In the C++Builder 10.4.1 RAD Studio IDE, open the Python_D.dproj package project file (you’ll find it in the “python4delphi-master\Packages\Delphi\Delphi 10.4+” folder).
Step 3 – Add an $IFDEF around the requires DesignIDE unit
Look at the Python_D.dpk source file, if you don’t see an $IFDEF around the DesignIDE unit, add it to avoid a compiler error when using the Win64 C++ compiler – DesignIDE is only required for Win32 since the IDE is a 32-bit Windows app.
Notice (in the source code above) that the LibSuffix Delphi compiler directive is set to “AUTO”. This can be done in source code or in the Project | Options | Description page (in the image below) to match the package file suffix with other compiled package files. The suffix is applied before the file extension. In drop down list, you can select the $(Auto) option for the suffix to represent the compiler version suffix for binary package files.
There is a separate Python_D.dpk package source file for versions 10.3 and earlier in the “python4delphi-master\Packages\Delphi\Delphi 10.3-” folder. In this package source file there are $IFDEFs to set the LIBSUFFIX for several recent Delphi compiler releases.
If you are going to use this earlier Python_D.dpk project you may need to comment out (or remove) the “{$R *.res}” statement at the front of the package source file (it may have already been removed in the latest commit of Python4Delphi).
Step 4a – Build and Install the Python4Delphi components with RAD Studio
There are two ways to build and install the components depending on whether you have RAD Studio or one of the C++Builder editions. If you only have C++Builder skip to “Step 4b” to learn how to use the Delphi command line compilers for Win32 and Win64.
Set the Python4Delphi Project Options for the Delphi Compiler | C/C++ Output file generation for Win32 and Win64 platform (all configurations – debug and release). Build and Install the Python4Delphi components for Win32 and Win64 targets.
Building and installing the components will make sure you have the generated C++ header files, package import library files and package static library files for your C++ VCL Win32 and Win64 projects.
From the help file: the “Generate all C++Builder files (including package libs)” option generates the package and all Delphi pieces, along with all necessary header files (.hpp), package import library file (.bpi), and package static library file (.lib and .a) for C++ projects. This is the default in desktop platforms.
Set the Delphi Compiler Search Path to include the Python4Delphi source directory so that the compiler will find any required include files and other files.
Step 4b – Use the Delphi command line compilers to Build and Installing the components
You can use batch files (or other script files) that run the Delphi command line compilers for Win32 (DCC32.exe) and Win64 (DCC64.exe). These Delphi compilers (included in the bin folder) will build the Python4Delphi package file and create the C++ header files, compiled package file, static library and other files required for use in your C++ applications.
In the C++Builder IDE, use the Components | Install Packages menu item and click the “Add…” button.
Navigate to the C:\Users\Public\Documents\Embarcadero\Studio\21.0\Bpl folder (the number will depend on which version of C++Builder you have) and select the Design time package (BPL) file and click the Open button. This will add the package and components to the IDE. You’ll now see “Components for Python” in the list of Design time packages. Highlight the entry and click the Components button to display the list of components in the package.
Step 4c – Verify that the generated Python4Delphi files for C++ use are generated
After you compile the Python4Delphi package project for Win32 and Win64 target platforms the following files will be generated:
In the IDE you’ll now see the components in the Component Palette window.
Building Your First C++Builder Python4Delphi VCL Application
Using RAD Studio, I opened the Python4Delphi Demo1 Delphi project and tested it to make sure that I had the components and Python working. C:\Users\david\Documents\Embarcadero\Studio\Projects\Python4Delphi\python4delphi-master\Demos\Demo01
Use File | New | C++Builder VCL application to create a starting C++Builder project (note: the source code for the project is in a zip file listed in the References section). I copied all of the components from the Delphi version of the Demo01 form file.
Demo01Unit.dfm file
object Form2: TForm2
Left = 0
Top = 0
Caption = 'Demo 01 Python (C++, VCL)'
ClientHeight = 344
ClientWidth = 534
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object Splitter1: TSplitter
Left = 0
Top = 153
Width = 534
Height = 3
Cursor = crVSplit
Align = alTop
Color = clBtnFace
ParentColor = False
ExplicitWidth = 536
end
object Memo1: TMemo
Left = 0
Top = 156
Width = 534
Height = 144
Align = alClient
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -13
Font.Name = 'Consolas'
Font.Pitch = fpVariable
Font.Style = []
Lines.Strings = (
'print(2+2)')
ParentFont = False
ScrollBars = ssBoth
TabOrder = 0
end
object Panel1: TPanel
Left = 0
Top = 300
Width = 534
Height = 44
Align = alBottom
BevelOuter = bvNone
TabOrder = 1
object Button1: TButton
Left = 0
Top = 6
Width = 115
Height = 25
Caption = 'Execute script'
TabOrder = 0
OnClick = Button1Click
end
object Button2: TButton
Left = 167
Top = 6
Width = 91
Height = 25
Caption = 'Load script...'
TabOrder = 1
OnClick = Button2Click
end
object Button3: TButton
Left = 264
Top = 8
Width = 89
Height = 25
Caption = 'Save script...'
TabOrder = 2
OnClick = Button3Click
end
end
object Memo2: TMemo
Left = 0
Top = 0
Width = 534
Height = 153
Align = alTop
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -13
Font.Name = 'Consolas'
Font.Pitch = fpVariable
Font.Style = []
ParentFont = False
ScrollBars = ssBoth
TabOrder = 2
end
object PythonEngine1: TPythonEngine
IO = PythonGUIInputOutput1
Left = 32
Top = 32
end
object OpenDialog1: TOpenDialog
DefaultExt = '*.py'
Filter = 'Python files|*.py|Text files|*.txt|All files|*.*'
Title = 'Open'
Left = 240
Top = 32
end
object SaveDialog1: TSaveDialog
DefaultExt = '*.py'
Filter = 'Python files|*.py|Text files|*.txt|All files|*.*'
Title = 'Save As'
Left = 328
Top = 32
end
object PythonGUIInputOutput1: TPythonGUIInputOutput
UnicodeIO = True
RawOutput = False
Output = Memo2
Left = 128
Top = 32
end
end
Compile and Run the C++ VCL Demo program and try some Python code
In the TMemo at the bottom of the form, type in some Python code. In my example I print the sum of two numbers, print the value of Pi from the Python math library and print the Python version # from the Python platform library. You can also use the Load and Save script buttons to bring up dialog boxes to load and save Python script files. Click the Execute script button to see the results show up in the upper TMemo.
Delphi 32-bit compiler (DCC32.exe) cmd line help (from C++Builder Community Edition 10.3.3)
Embarcadero Delphi for Win32 compiler version 33.0
Copyright (c) 1983,2018 Embarcadero Technologies, Inc.
Syntax: dcc32 [options] filename [options]
-A<unit>=<alias> = Set unit alias
-B = Build all units
-CC = Console target
-CG = GUI target
-D<syms> = Define conditionals
-E<path> = EXE/DLL output directory
-F<offset> = Find error
-GD = Detailed map file
-GP = Map file with publics
-GS = Map file with segments
-H = Output hint messages
-I<paths> = Include directories
-J = Generate .obj file
-JPHNE = Generate C++ .obj file, .hpp file, in namespace, export all
-JL = Generate package .lib, .bpi, and all .hpp files for C++
-K<addr> = Set image base addr
-LE<path> = package .bpl output directory
-LN<path> = package .dcp output directory
-LU<package> = Use package
-M = Make modified units
-NU<path> = unit .dcu output directory
-NH<path> = unit .hpp output directory
-NO<path> = unit .obj output directory
-NB<path> = unit .bpi output directory
-NX<path> = unit .xml output directory
-NS<namespaces> = Namespace search path
-O<paths> = Object directories
-P = look for 8.3 file names also
-Q = Quiet compile
-R<paths> = Resource directories
-TX<ext> = Output name extension
-U<paths> = Unit directories
-V = Debug information in EXE
-VR = Generate remote debug (RSM)
-VT = Debug information in TDS
-VN = TDS symbols in namespace
-W[+|-|^][warn_id] = Output warning messages
-Z = Output 'never build' DCPs
-$<dir> = Compiler directive
--help = Show this help screen
--version = Show name and version
--codepage:<cp> = specify source file encoding
--default-namespace:<namespace> = set namespace
--depends = output unit dependency information
--doc = output XML documentation
--drc = output resource string .drc file
--no-config = do not load default dcc32.cfg file
--description:<string> = set executable description
--inline:{on|off|auto} = function inlining control
--legacy-ifend = allow legacy $IFEND directive
--zero-based-strings[+|-] = strings are indexed starting at 0
--peflags:<flags> = set extra PE Header flags field
--peoptflags:<flags> = set extra PE Header optional flags field
--peosversion:<major>.<minor> = set OS Version fields in PE Header (default: 5.0)
--pesubsysversion:<major>.<minor> = set Subsystem Version fields in PE Header (default: 5.0)
--peuserversion:<major>.<minor> = set User Version fields in PE Header (default: 0.0)
--lib-version:<version> = Output package name version
--lib-suffix:<suffix> = Output package name suffix
Compiler switches: -$<letter><state> (defaults are shown below)
A8 Aligned record fields
B- Full boolean Evaluation
C+ Evaluate assertions at runtime
D+ Debug information
G+ Use imported data references
H+ Use long strings by default
I+ I/O checking
J- Writeable structured consts
L+ Local debug symbols
M- Runtime type info
O+ Optimization
P+ Open string params
Q- Integer overflow checking
R- Range checking
T- Typed @ operator
U- Pentium(tm)-safe divide
V+ Strict var-strings
W- Generate stack frames
X+ Extended syntax
Y+ Symbol reference info
Z1 Minimum size of enum types
Stack size: -$M<minStackSize[,maxStackSize]> (default 16384,1048576)
Delphi 64-bit compiler (DCC64.exe) cmd line help (C++Builder Community Edition 10.3.3)
Embarcadero Delphi for Win64 compiler version 33.0
Copyright (c) 1983,2018 Embarcadero Technologies, Inc.
Syntax: dcc64 [options] filename [options]
-A<unit>=<alias> = Set unit alias
-B = Build all units
-CC = Console target
-CG = GUI target
-D<syms> = Define conditionals
-E<path> = EXE/DLL output directory
-F<offset> = Find error
-GD = Detailed map file
-GP = Map file with publics
-GS = Map file with segments
-H = Output hint messages
-I<paths> = Include directories
-J = Generate .obj file
-JPHNE = Generate C++ .obj file, .hpp file, in namespace, export all
-JL = Generate package .lib, .bpi, and all .hpp files for C++
-K<addr> = Set image base addr
-LE<path> = package .bpl output directory
-LN<path> = package .dcp output directory
-LU<package> = Use package
-M = Make modified units
-NU<path> = unit .dcu output directory
-NH<path> = unit .hpp output directory
-NO<path> = unit .obj output directory
-NB<path> = unit .bpi output directory
-NX<path> = unit .xml output directory
-NS<namespaces> = Namespace search path
-O<paths> = Object directories
-P = look for 8.3 file names also
-Q = Quiet compile
-R<paths> = Resource directories
-TX<ext> = Output name extension
-U<paths> = Unit directories
-V = Debug information in EXE
-VR = Generate remote debug (RSM)
-VT = Debug information in TDS
-VN = TDS symbols in namespace
-W[+|-|^][warn_id] = Output warning messages
-Z = Output 'never build' DCPs
-$<dir> = Compiler directive
--help = Show this help screen
--version = Show name and version
--codepage:<cp> = specify source file encoding
--default-namespace:<namespace> = set namespace
--depends = output unit dependency information
--doc = output XML documentation
--drc = output resource string .drc file
--no-config = do not load default dcc64.cfg file
--description:<string> = set executable description
--inline:{on|off|auto} = function inlining control
--legacy-ifend = allow legacy $IFEND directive
--zero-based-strings[+|-] = strings are indexed starting at 0
--peflags:<flags> = set extra PE Header flags field
--peoptflags:<flags> = set extra PE Header optional flags field
--peosversion:<major>.<minor> = set OS Version fields in PE Header (default: 5.0)
--pesubsysversion:<major>.<minor> = set Subsystem Version fields in PE Header (default: 5.0)
--peuserversion:<major>.<minor> = set User Version fields in PE Header (default: 0.0)
--lib-version:<version> = Output package name version
--lib-suffix:<suffix> = Output package name suffix
Compiler switches: -$<letter><state> (defaults are shown below)
A8 Aligned record fields
B- Full boolean Evaluation
C+ Evaluate assertions at runtime
D+ Debug information
G+ Use imported data references
H+ Use long strings by default
I+ I/O checking
J- Writeable structured consts
L+ Local debug symbols
M- Runtime type info
O+ Optimization
P+ Open string params
Q- Integer overflow checking
R- Range checking
T- Typed @ operator
V+ Strict var-strings
W- Generate stack frames
X+ Extended syntax
Y+ Symbol reference info
Z1 Minimum size of enum types
Stack size: -$M<minStackSize[,maxStackSize]> (default 16384,1048576)
C++ Demo project and Delphi command line package build batch files (zip file)
Do you need to add printer support to your C++ applications using the Visual Component Library (VCL) or FireMonkey (FMX) GUI ? In this blog post I’ll show you how to build Windows applications that support printing image bitmaps using the VCL and FMX frameworks. One of my favorite C++Builder RTL features is that both frameworks provide similar printer components and ways of programming with only a few subtle differences.
Build VCL and FMX Application Projects
Use the “File | New | Windows VCL Application – C++Builder” menu item and create a starting C++ VCL application. Save the product to a folder.
File | New | Windows VCL Application – C++Builder
Next, in the Project Window, right mouse click on the ProjectGroup node and select the “Add New Project…” menu item.
Add New Project to the Project Group
In the popup dialog choose to create a Multi-Device Application.
Add New Multi-Device Application
Click the OK button and on the next screen choose to create a “Blank Application”.
Multi-Device Project templates list – choose Blank Application
Use the File | Save All menu item (or type Shift+Ctrl+S) to save both starting projects and the project group to a folder.
Project Group with VCL and FMX Starting Projects
Each of the VCL and FMX projects have a main form (.dfm and .fmx extensions respectively). While most of the IDE will look the same, if you select each form’s unit you will see different looks for each of their form designers.
VCL Form DesignerFMX Form Designer
There are many videos, articles and help files that describe the details of each designer (check out links in the reference section below). For now, let’s dig into the VCL and FMX printer examples I’ve created.
A Simple UI for each Printer Test Project
On each of the VCL and FMX main forms you’ll see the following components.
VCL form’s components in the Structure WindowFMX form’s components in the Structure Window
Each project’s main menu contains a File and Destination menu. The Destination menu item allows the user to choose to override the printing destination (Printer or File).
The File menu provides an OpenPictureDialog (VCL) or OpenDialog (FMX), PrintPicture dialog for choosing the printer and other printing options, PrinterSetup dialog to set additional printer setup options, Panel (aligned to the top of the form)with a label and ComboBox which will list the available printer device names, and an Image component (aligned to the client area) to contain the picture bitmap.
The VCL and FMX forms look like the following.
VCL app form with componentsFMX app form with components
Right mouse click on the form and choose “View as Text” from the popup menu. Now you can see all of the form and component properties and sub-properties that have been set from their default values. You can also make changes in this text form mode but be careful to not make any errors.
To switch back to the form mode click the right mouse button (or hit Alt-F12) and choose “View as Form” from the popup menu.
VCLPrintUnit.dfm (View as Text)
object MainVCLForm: TMainVCLForm
Left = 0
Top = 0
Caption = 'Printer Test (C++, VCL)'
ClientHeight = 473
ClientWidth = 667
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
Menu = MainMenu1
OldCreateOrder = False
OnShow = FormShow
PixelsPerInch = 96
TextHeight = 13
object Image1: TImage
Left = 0
Top = 41
Width = 667
Height = 432
Align = alClient
Proportional = True
ExplicitLeft = 104
ExplicitTop = 102
ExplicitWidth = 424
ExplicitHeight = 317
end
object Panel1: TPanel
Left = 0
Top = 0
Width = 667
Height = 41
Align = alTop
TabOrder = 0
object Label1: TLabel
Left = 10
Top = 12
Width = 41
Height = 13
Caption = 'Printers:'
end
object PrintersComboBox: TComboBox
Left = 57
Top = 9
Width = 250
Height = 21
TabOrder = 0
Text = 'PrintersComboBox'
end
end
object PrintDialog1: TPrintDialog
Options = [poPrintToFile]
Left = 176
Top = 56
end
object PrinterSetupDialog1: TPrinterSetupDialog
Left = 304
Top = 64
end
object OpenPictureDialog1: TOpenPictureDialog
DefaultExt = 'bmp'
InitialDir = 'c:\temp'
Left = 56
Top = 56
end
object MainMenu1: TMainMenu
Left = 424
Top = 64
object File1: TMenuItem
Caption = 'File'
object File2: TMenuItem
Caption = 'Open Picture'
OnClick = File2Click
end
object PrintPicture1: TMenuItem
Caption = 'Print Picture'
Enabled = False
OnClick = PrintPicture1Click
end
object PrinterSetup1: TMenuItem
Caption = 'Printer Setup'
Enabled = False
OnClick = PrinterSetup1Click
end
object PrintPicture2: TMenuItem
Caption = 'Exit'
OnClick = PrintPicture2Click
end
end
object Destination1: TMenuItem
Caption = 'Destination'
object PrintToPrinterDestinationMenuItem: TMenuItem
Caption = 'Print to Printer'
Checked = True
OnClick = PrintToPrinterDestinationMenuItemClick
end
object PrintToFileDestinationMenuItem: TMenuItem
Caption = 'Print to File'
OnClick = PrintToFileDestinationMenuItemClick
end
end
end
end
FMXPrintUnit.fmx (View as Text)
object MainFMXForm: TMainFMXForm
Left = 0
Top = 0
Caption = 'Printer Test (C++, FMX)'
ClientHeight = 380
ClientWidth = 640
Position = Designed
WindowState = wsMaximized
FormFactor.Width = 320
FormFactor.Height = 480
FormFactor.Devices = [Desktop]
OnShow = FormShow
DesignerMasterStyle = 0
object Image1: TImage
MultiResBitmap = <
item
end>
Align = Client
Size.Width = 640.000000000000000000
Size.Height = 339.000000000000000000
Size.PlatformDefault = False
end
object PrintDialog1: TPrintDialog
Options = [poPrintToFile]
Left = 68
Top = 40
end
object PrinterSetupDialog1: TPrinterSetupDialog
Left = 190
Top = 42
end
object OpenDialog1: TOpenDialog
DefaultExt = 'bmp'
Filter = '*.bmp'
InitialDir = 'c:\temp'
Left = 312
Top = 44
end
object MainMenu1: TMainMenu
Left = 418
Top = 46
object FileMenu: TMenuItem
Text = 'File'
object OpenBitmapMenuItem: TMenuItem
Locked = True
Text = 'Open Bitmap'
OnClick = OpenBitmapMenuItemClick
end
object PrintMenuItem: TMenuItem
Enabled = False
Locked = True
Text = 'Print'
OnClick = PrintMenuItemClick
end
object PrinterSetupMenuItem: TMenuItem
Enabled = False
Locked = True
Text = 'Printer Setup'
OnClick = PrinterSetupMenuItemClick
end
object ExitMenuItem: TMenuItem
Locked = True
Text = 'Exit'
OnClick = ExitMenuItemClick
end
end
object DestinationMenu: TMenuItem
Text = 'Destination'
object PrintToPrinterDestinationMenuItem: TMenuItem
Locked = True
IsChecked = True
Text = 'Print to Printer'
OnClick = PrintToPrinterDestinationMenuItemClick
end
object PrintToFileDestinationMenuItem: TMenuItem
Locked = True
Text = 'Print to File'
OnClick = PrintToFileDestinationMenuItemClick
end
end
end
object Panel1: TPanel
Align = Top
Size.Width = 640.000000000000000000
Size.Height = 41.000000000000000000
Size.PlatformDefault = False
object PrintersComboBox: TComboBox
Position.X = 72.000000000000000000
Position.Y = 8.000000000000000000
Size.Width = 233.000000000000000000
Size.Height = 22.000000000000000000
Size.PlatformDefault = False
end
object Label1: TLabel
Position.X = 8.000000000000000000
Position.Y = 9.000000000000000000
Size.Width = 57.000000000000000000
Size.Height = 17.000000000000000000
Size.PlatformDefault = False
Text = 'Printers:'
end
end
end
Additional comments about component properties and event handlers are included in the source code for the projects.
The Source Code
Below you will find the header files for the VCL and FMX form units. The header files will show the component declarations, event handlers and any public/private declarations.
Below you will find the source code for the VCL and FMX form units.
VCLPrinterUnit.cpp
//---------------------------------------------------------------------------
#include <vcl.h>
#include <Vcl.Imaging.GIFImg.hpp>
#include <Vcl.Imaging.jpeg.hpp>
#include <Vcl.Imaging.pngimage.hpp>
#include <Vcl.Printers.hpp>
#pragma hdrstop
#include "VCLPrintUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TMainVCLForm *MainVCLForm;
//---------------------------------------------------------------------------
__fastcall TMainVCLForm::TMainVCLForm(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::File2Click(TObject *Sender)
{
if (OpenPictureDialog1->Execute()) {
Image1->Picture->LoadFromFile(OpenPictureDialog1->FileName);
PictureLoaded = true;
PrintPicture1->Enabled = true;
PrinterSetup1->Enabled = true;
}
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::FormShow(TObject *Sender)
{
PictureLoaded = false;
PrintToPrinterDestinationMenuItem->Checked = true;
PrintToFileDestinationMenuItem->Checked = false;
// get printers list and put in combobox
PrintersComboBox->Items = Printer()->Printers;
// make the currently selected printer the Item in the ComboBox
PrintersComboBox->ItemIndex = 0;
for (int i = 0; i < Printer()->Printers->Count-1; i++) {
if (Printer()->Printers->Strings[Printer()->PrinterIndex] == PrintersComboBox->Items->Strings[i]) {
PrintersComboBox->ItemIndex = i;
}
}
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::PrintToPrinterDestinationMenuItemClick(TObject *Sender)
{
// set menu item checked for print to printer
PrintToPrinterDestinationMenuItem->Checked = true;
PrintToFileDestinationMenuItem->Checked = false;
// set PrintDialog PrintToFile checkbox off
// Note: to allow user to override the menu item - make sure
// PrintDialog Options poPrintToFile is set to true
// so that the PrintToFile checkbox appears in the dialog
PrintDialog1->PrintToFile = false;
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::PrintToFileDestinationMenuItemClick(TObject *Sender)
{
// set menu item checked for print to file
PrintToPrinterDestinationMenuItem->Checked = false;
PrintToFileDestinationMenuItem->Checked = true;
// set PrintDialog PrintToFile checkbox on
// Note: to allow user to override the menu item - make sure
// PrintDialog Options poPrintToFile is set to true
// so that the PrintToFile checkbox appears in the dialog
PrintDialog1->PrintToFile = true;
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::PrintPicture1Click(TObject *Sender)
{
// check if a picture is loaded
if (PictureLoaded) {
if (PrintDialog1->Execute()) {
// Call BeginDoc - to get the dimensions for selected printer
Printer()->BeginDoc();
try {
// use StretchDraw to do full size bitmap printing
// notes:
// printer settings can be made using the
// PrintDialog and PrinterSetupDialog
// you can also control page layout in code:
// Property is Orientation:
// poPortrait
// poLandscape
Printer()->Canvas->StretchDraw(
Rect(0, 0, Printer()->PageWidth,Printer()->PageHeight),
Image1->Picture->Graphic);
}
__finally {
// end the document and the printing will begin
Printer()->EndDoc();
}
}
}
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::PrinterSetup1Click(TObject *Sender)
{
// Printer Setup
PrinterSetupDialog1->Execute();
}
//---------------------------------------------------------------------------
void __fastcall TMainVCLForm::PrintPicture2Click(TObject *Sender)
{
Application->Terminate();
}
//---------------------------------------------------------------------------
FMXPrinterUnit.cpp
//---------------------------------------------------------------------------
#include <fmx.h>
#include "FMX.Printer.hpp"
#include "System.SysUtils.hpp"
#pragma hdrstop
#include "FMXPrintUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.fmx"
TMainFMXForm *MainFMXForm;
//---------------------------------------------------------------------------
__fastcall TMainFMXForm::TMainFMXForm(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::PrintMenuItemClick(TObject *Sender)
{
TRectF SrcRect, DestRect;
if (PrintDialog1->Execute()) {
// Set the default DPI for the printer. The SelectDPI routine defaults
// to the closest available resolution as reported by the driver.
// Printer->ActivePrinter->SelectDPI(1200, 1200);
// Printer->ActivePrinter->ActiveDPIIndex = 1; // you can also the DPI index
// Set canvas filling style
// Printer->Canvas->Fill->Color = claBlack;
// Printer->Canvas->Fill->Kind = TBrushKind(1);
// Start printing
Printer::Printer()->BeginDoc();
// Set the Source and Destination TRects
SrcRect = TRectF(0, 0, Image1->Bitmap->Width, Image1->Bitmap->Height);
DestRect = TRectF(0, 0, Printer::Printer()->PageWidth, Printer::Printer()->PageHeight);
// Print the picture, on all the surface of the page and all opaque.
Printer::Printer()->Canvas->DrawBitmap(Image1->Bitmap, SrcRect, DestRect, 1);
// Finish the printing job
Printer::Printer()->EndDoc();
}
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::OpenBitmapMenuItemClick(TObject *Sender)
{
// open a bitmap for printing
if (OpenDialog1->Execute()) {
Image1->Bitmap->LoadFromFile(OpenDialog1->FileName);
PrintMenuItem->Enabled = true;
PrinterSetupMenuItem->Enabled = true;
PictureLoaded = true;
}
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::ExitMenuItemClick(TObject *Sender)
{
// exit the application
Application->Terminate();
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::PrinterSetupMenuItemClick(TObject *Sender)
{
// use the Printer Setup dialog box
PrinterSetupDialog1->Execute();
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::FormShow(TObject *Sender)
{
// on form show event handler
PictureLoaded = false;
PrintToPrinterDestinationMenuItem->IsChecked = true;
PrintToFileDestinationMenuItem->IsChecked = false;
// populate the ComboBox with the printer device names
PrintersComboBox->ItemIndex = 0;
for (int i = 0; i < Printer::Printer()->Count-1; i++) {
PrintersComboBox->Items->Add(Printer::Printer()->Printers[i]->Title);
// set the ComboBox ItemIndex to the active printer
if (Printer::Printer()->Printers[i]->Title == Printer::Printer()->ActivePrinter->Title) {
PrintersComboBox->ItemIndex = i;
}
}
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::PrintToPrinterDestinationMenuItemClick(TObject *Sender)
{
// set menu item checked for print to printer
PrintToPrinterDestinationMenuItem->IsChecked = true;
PrintToFileDestinationMenuItem->IsChecked = false;
// set PrintDialog PrintToFile checkbox off
// Note: to allow user to override the menu item - make sure
// PrintDialog Options poPrintToFile is set to true
// so that the PrintToFile checkbox appears in the dialog
PrintDialog1->PrintToFile = false;
}
//---------------------------------------------------------------------------
void __fastcall TMainFMXForm::PrintToFileDestinationMenuItemClick(TObject *Sender)
{
// set menu item checked for print to file
PrintToPrinterDestinationMenuItem->IsChecked = false;
PrintToFileDestinationMenuItem->IsChecked = true;
// set PrintDialog PrintToFile checkbox on
// Note: to allow user to override the menu item - make sure
// PrintDialog Options poPrintToFile is set to true
// so that the PrintToFile checkbox appears in the dialog
PrintDialog1->PrintToFile = true;
}
//---------------------------------------------------------------------------
C++Builder Product Page – Native Apps that Perform. Build Windows C++ Apps 10x Faster with Less Code
C++Builder Product Editions – C++Builder is available in four editions – Professional, Enterprise, Architect and Community (free). C++Builder is also available as part of the RAD Studio development suite.
From his CppCon 2020 talk description: This is an exploration of a design space close to the hardware and of the use of C++ in that space, rather than a standards proposal or the presentation of a mature tool chain. And, no, by “primitive”, I don’t mean “old-fashioned, C-like” code; some of the general techniques are old, but some of the code requires C++17 and much could be done better given features we are unlikely to get even in C++23.
Links to other replays of Bjarne’s talks at past CppCon (the C++ conference) events
You will find ISO C++ articles, news, books, podcasts, training courses, events, videos, product news, standardization activities, etc. on the Standard C++ Foundation site.
It’s been almost 50 years since I took a Linear Algebra and Matrices course as one of my Computer Science electives at Cal Poly San Luis Obispo, CA. The textbook for the course was “Mathematics Of Matrices: First Book Of Matrix Theory And Linear Algebra” by Philip J Davis. While I have used arrays and vectors in many programming projects, I have to be honest and say that I have not used a lot of matrix math in my code.
Now that the Eigen C++ Template Library is available for download inside the C++Builder IDE using the GetIt Package Manager, I decided to re-introduce myself to matrix math, manipulations and linear algebra (not bad for a 69 year old software engineer). This blog post will show C++ developers how to download, install and use the Eigen C++ library using C++Builder and VCL.
Installing Eigen via the GetIt Package Manager
Inside the C++Builder IDE, use the Tools | GetIt Project Manager menu item to bring up the list of available add-on components, libraries and demos. Type “Eigen” in the search box to see what is available.
Click the Install button to download, install, build and run tests the Eigen C++ library with your release of C++Builder (I used C++Builder version 10.4.1). As part of the Eigen installation you will see two additional windows.
Dependency notice about minimal changes made to allow Eigen to work with C++BuilderEigen Installation Window showing progress of the download, installation and tests
Once the download and installation is completed, you can start using Eigen in your applications. To learn more about the Eigen C++ Template Library I’ve included some reference links at the end of this post. To dust off my matrix and linear algebra cobwebs and learn a little bit about Eigen, I created three sample C++Builder VCL applications using Eigen.
Simple Eigen Test C++ VCL Application
This first example Button onClick event handler displays the Eigen version number, creates a 3×3 matrix, populates it with random floating point numbers (between -1 and 1) and uses the addition, subtraction and multiplication operators.
The VCL Form containing a button and memoApplication Output using addition, subtraction and multiplication
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include <Eigen/Dense>
using Eigen::MatrixXd;
using Eigen::IOFormat;
#include "MainUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
// create string stream from Eigen Matrix
static std::string ConvertToString(const Eigen::MatrixXd& mat){
std::stringstream ss;
IOFormat CleanFmt(Eigen::FullPrecision, 0, ", ", "\n", "[", "]");
ss << mat.format(CleanFmt);
return ss.str();
}
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
// first sample app adapted from Eigen documentation and put in VCL app
// display Eigen version number
EigenVersionLabel->Caption = "Eigen version: "
+ IntToStr(EIGEN_WORLD_VERSION)
+ "."
+ IntToStr(EIGEN_MAJOR_VERSION)
+ "."
+ IntToStr(EIGEN_MINOR_VERSION);
// define a 3x3 matrix of doubles
MatrixXd m(3,3);
// Fill matrix with random numbers between -1 and +1
m.setRandom(3,3);
// Change three matrix items using + - and *
m(0,2) = m(0,0) + m(0,1);
m(1,2) = m(1,0) - m(1,1);
m(2,2) = m(2,0) * m(2,1);
// output matrix using strings
MatrixOutputMemo->Lines->Clear();
MatrixOutputMemo->Lines->Text = ConvertToString(m).c_str();
}
//---------------------------------------------------------------------------
Matrix Operations C++ VCL Application
The second Eigen C++ VCL application exercises several Eigen operations including adding and subtracting two matricies, multiplying and dividing a matrix by a scalar, multiplying two matricies, transposing a matrix, invert a matrix and sum all elements of a matrix. There are many additional features to explore in Eigen for vector and matrix operations.
In the UI for the application you’ll see a RadioGroup for selecting one of the operations, three StringGrids to display matrix contents, an EditBox for inputing a scalar (I used Pi), and a Label for the summing result.
The Matrix Operations example VCL formExample Output after subtracting the x and y matrices giving z
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include <Eigen/Dense>
using Eigen::MatrixXd;
#include <System.SysUtils.hpp>
#include "MainUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
MatrixXd x(3,3);
MatrixXd y(3,3);
MatrixXd z(3,3);
void TForm1::displayMatricies() {
// display contents of x, y and z matricies
int numberRows = x.rows();
int numberColumns = y.cols();
for (int r=0 ; r < numberRows ; r++) {
for (int c = 0; c < numberColumns; c++) {
StringGridX->Cells[r][c] = FloatToStrF(x(r,c),ffFixed,5,3);
StringGridY->Cells[r][c] = FloatToStrF(y(r,c),ffFixed,5,3);
StringGridZ->Cells[r][c] = FloatToStrF(z(r,c),ffFixed,5,3);
}
}
}
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormShow(TObject *Sender)
{
// populate x and y matricies and their string grids with random numbers
x.setRandom(5,5);
y.setRandom(5,5);
z.setZero(5,5);
// clear selections in the string grids
TGridRect gr;
gr.Left = StringGridX->ColCount;
gr.Top = StringGridX->RowCount;
StringGridX->Canvas->Brush->Color = clWindow;
StringGridX->Canvas->FillRect(Rect(StringGridX->Left,StringGridX->Width,StringGridX->Top,StringGridX->Height));
gr.Left = StringGridY->ColCount;
gr.Top = StringGridY->RowCount;
StringGridY->Canvas->Brush->Color = clWindow;
StringGridY->Canvas->FillRect(Rect(StringGridY->Left,StringGridY->Width,StringGridY->Top,StringGridY->Height));
gr.Left = StringGridZ->ColCount;
gr.Top = StringGridZ->RowCount;
StringGridZ->Canvas->Brush->Color = clWindow;
StringGridZ->Canvas->FillRect(Rect(StringGridZ->Left,StringGridZ->Width,StringGridZ->Top,StringGridZ->Height));
// display current values of matricies
displayMatricies();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
// do the operation that is currently selected in the Radio Button Group
// 0 = addition, 1= subtraction, 2 = multiplication,
// 3 = division, 4 = dot product
switch(RadioGroup1->ItemIndex) {
case 0: // addition
z = x + y;
break;
case 1: // subtraction
z = x - y;
break;
case 2: // multiply x by scalar and save result in z
z = x * StrToFloat(ScalarEdit->Text);
break;
case 3: // divide x by scalar and save result in z
z = x / StrToFloat(ScalarEdit->Text);
break;
case 4: // multiply x * y and save result in z
z.noalias() = x * y;
break;
case 5: // transpose x and save result in z
z = x.transpose();
break;
case 6: // invert x and save result in z
z = x.inverse();
break;
case 7: // sum all elements of x and save in result
ResultLabel->Caption = "Result: "+FloatToStr(x.sum());
break;
}
// display current values of matricies
displayMatricies();
}
//---------------------------------------------------------------------------
Shopping Linear Algebra C++ VCL Application
I wanted to use a “real world” linear algebra example to showcase a few additional features of the Eigen C++ template library. There are many matrix and linear algebra courses and examples out on the Internet. After a quick search I decided to use “Real-world Applications of Linear Algebra Tools” by E. Ulrychova, postgradual student at the University of Economics, Department of Mathematics, Prague, Czech Republic.
The scenario has three people who want to each shop for baked goods at only one of two stores. Each person has a quantity of rolls, buns, cakes and breads that they want to purchase. Each store has a list of prices that they charge for each of the baked goods. This linear algebra example calculates a spending analysis for each person at each store to show where each person should shop.
The user interface includes a button to run code that calculates the lowest shopping cost for each person, a StringGrid for the baked goods demand matrix for each person, a StringGrid for the store pricing for each baked good, and a StringGrid for the results of the optimal spending analysis for each person.
The VCL Form for the UIThe demand matrix of baked goods for each person, the prices for each baked good by shop and the resulting optimal shop spending for each person
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include <Eigen/Dense>
using Eigen::MatrixXd;
using Eigen::VectorXd;
using Eigen::IOFormat;
#include "ShoppingUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
// Calculate results of spending analysis by person by store
// R = PQ
// from:
// Real-world Applications of Linear Algebra Tools
// by E. Ulrychova, postgradual student
// University of Economics, Department of Mathematics, Prague, Czech Republic
// https://www.mff.cuni.cz/veda/konference/wds/proc/pdf06/WDS06_106_m8_Ulrychova.pdf
int r,c; // row and column indexes used throughout this event handler
// matricies used for spending analysis
MatrixXd DemandMatrix(4,3); // Q
MatrixXd PriceMatrix(2,4); // P
MatrixXd ResultMatrix(2,3); // R
// vectors used for dot product analysis of spending by person by shop
VectorXd DemandVector(4);
VectorXd PriceVector(4);
// Demanded quantity of foodstuffs per person (3 people, 4 foodstuffs)
DemandMatrix << // Q
6,3,3, // foodstuff quantities for rolls for each of the 3 people
5,6,4, // foodstuff quantities for buns for each of the 3 people
3,2,3, // foodstuff quantities for cakes for each of the 3 people
1,2,1; // foodstuff quantities for breads for each of the 3 people
// Prices for each foodstuff in each shop (4 foodstuffs, 2 shops)
PriceMatrix << //P
1.50,2.00,5.00,16.00, // prices for foodstuffs at Shop 1
1.00,2.50,4.50,17.00; // prices for foodstuffs at Shop 2
// Calculate results of spending analysis by person by store
// R = PQ
int ResultMatrixNumberRows = ResultMatrix.rows();
int ResultMatrixNumberColumns = ResultMatrix.cols();
for (r=0 ; r < ResultMatrixNumberRows ; r++) {
for (c = 0; c < ResultMatrixNumberColumns; c++) {
// create price and demand vectors
DemandVector = DemandMatrix.col(c);
PriceVector = PriceMatrix.row(r);
// use dot product of demand and price to get a result
ResultMatrix(r,c) = DemandVector.dot(PriceVector);
}
}
// set heading and column strings for Demand Matrix rows and columns
DemandMatrixStringGrid->Cells[1][0] = "roll";
DemandMatrixStringGrid->Cells[2][0] = "bun";
DemandMatrixStringGrid->Cells[3][0] = "cake";
DemandMatrixStringGrid->Cells[4][0] = "bread";
DemandMatrixStringGrid->Cells[0][1] = "p1";
DemandMatrixStringGrid->Cells[0][2] = "p2";
DemandMatrixStringGrid->Cells[0][3] = "p3";
// set heading and column strings for Price Matrix rows and columns
PriceMatrixStringGrid->Cells[1][0] = "s1";
PriceMatrixStringGrid->Cells[2][0] = "s1";
PriceMatrixStringGrid->Cells[0][1] = "roll";
PriceMatrixStringGrid->Cells[0][2] = "bun";
PriceMatrixStringGrid->Cells[0][3] = "cake";
PriceMatrixStringGrid->Cells[0][4] = "bread";
// set heading and column strings for Result Matrix String Grid rows and columns
ResultStringGrid->Cells[1][0] = "s1";
ResultStringGrid->Cells[2][0] = "s1";
ResultStringGrid->Cells[0][1] = "p1";
ResultStringGrid->Cells[0][2] = "p2";
ResultStringGrid->Cells[0][3] = "p3";
int DemandMatrixNumberRows = DemandMatrix.rows();
int DemandMatrixNumberColumns = DemandMatrix.cols();
// populate string grid with the Demand Data
for (r=1 ; r <= DemandMatrixNumberRows ; r++) {
for (c = 1; c <= DemandMatrixNumberColumns; c++) {
DemandMatrixStringGrid->Cells[r][c] = FloatToStrF(DemandMatrix(r-1,c-1),ffFixed,5,3);
}
}
int PriceMatrixNumberRows = PriceMatrix.rows();
int PriceMatrixNumberColumns = PriceMatrix.cols();
// populate string grid with the Price Data
for (r=1 ; r <= PriceMatrixNumberRows ; r++) {
for (c = 1; c <= PriceMatrixNumberColumns; c++) {
PriceMatrixStringGrid->Cells[r][c] = FloatToStrF(PriceMatrix(r-1,c-1),ffFixed,5,3);
}
}
// With the supplied data this program shows it is optimal
// for person p1 to buy in the shop s2,
// for person p2 to buy in shop s1
// and person p3 will pay the same price in shop s1 and s2
int ResultNumberRows = ResultMatrix.rows();
int ResultNumberColumns = ResultMatrix.cols();
// populate string grid with the results
for (r=1 ; r <= ResultNumberRows ; r++) {
for (c = 1; c <= ResultNumberColumns; c++) {
ResultStringGrid->Cells[r][c] = FloatToStrF(ResultMatrix(r-1,c-1),ffFixed,5,3);
}
}
}
//---------------------------------------------------------------------------
C++Builder Product Page – Native Apps that Perform. Build Windows C++ Apps 10x Faster with Less Code
C++Builder Product Editions – C++Builder is available in four editions – Professional, Enterprise, Architect and Community (free). C++Builder is also available as part of the RAD Studio development suite.
There’s lots of ISO C++ news and content happening including the unanimous voting approval of ISO C++20, CppCon2020 (starts Monday September 13, 2020) with Bjarne Stroustrup’s opening keynote “The Power and Beauty of Primitive C++”, TIOBE’s Index for September 2020 headline “Programming Language C++ is doing very well”, C++ programming tips and tricks articles and more.
Links to recent ISO C++ news and articles
CppCon 2020 Opening Keynote – The Beauty and Power of “Primitive” C++ – this keynote is an exploration of a design space close to the hardware and of the use of C++ in that space, rather than a standards proposal or the presentation of a mature tool chain. And, no, by “primitive”, I don’t mean “old-fashioned, C-like” code; some of the general techniques are old, but some of the code requires C++17 and much could be done better given features we are unlikely to get even in C++23. Monday, September 14, 2020 8:45 to 10:00 MDT(Mountain Daylight Time).
TIOBE Index for September 2020 – Headline: “Programming Language C++ is doing very well” – Compared to last year, C++ is now the fastest growing language of the pack (+1.48%). I think that the new C++20 standard might be one of the main causes for this. Especially because of the new modules feature that is going to replace the dreadful include mechanism. C++ beats other languages with a positive trend such as R (+1.33%) and C# (+1.18%).
C++20 approved, C++23 meetings and schedule update by Herb Sutter – On Friday September 4, C++20’s DIS (Draft International Standard) ballot ended, and it passed unanimously. This means that C++20 has now received final technical approval and is done with ISO balloting, and we expect it to be formally published toward the end of 2020 after we finish a final round of ISO editorial work.
Concept archetypes by Andrzej Krzemieński – Concepts in the form added in C++20 used to be called lite. This is because they do not provide one quite important functionality: having the compiler check if the author of a constrained template is only using operations and types allowed by the constraining concept. In other words, we can say that our template only requires operations A and B to be valid, but we can still use some other operations inside and this is fine with the compiler. In this post we will show how this is problematic, even for programmers aware of the issue, and how to address it with concept archetypes.
6 Efficient Things You Can Do to Refactor a C++ Project by Bartlomiej Filipe (Bartek) – Bartek took his old pet project from 2006, experimented, refactored it and made it more “modern C++”. This article contains lessons learned and six practical steps that you can apply in your projects.
volatile and Other Small Improvements in C++20 by Rainer Grimm – This article completes Rainer’s tour through the C++20 core language features with a few small improvements. One interesting of these minor improvements is that most of volatile has been deprecated.
The implication of const or reference member variables in C++ by Lesley Lai – In the conventional wisdom of the C++ community, non-static const or reference data variables are considered problematic. There are solid reasons on why you should avoid const or reference member variables in C++. Nevertheless, like many things in C++, “avoid” does not mean “never use.” And they can occasionally still find some uses.
Using Vim for C++ Development by Adem Budak – Adem shares how he uses Vim as C++ development environment, adding things like code completion, linting, formatting and snippet support. If you come from the IDE land and have been set your options with the checkbox on a GUI, you might need a mental shift to use text based configuration tools, like Vim.
LLVM 10 bolsters Wasm, C/C++, and TensorFlow by Serdar Yegulalp – LLVM 10, an upgrade of the open source compiler framework behind a number of language runtimes and toolchains, is available today after a number of delays. The biggest addition to LLVM 10 is support for MLIR, a sublanguage that compiles to LLVM’s internal language and is used by projects like TensorFlow to efficiently represent how data and instructions are handled. Accelerating TensorFlow with LLVM directly is clumsy; MLIR provides more useful programming metaphors for such projects.
Two VCL Example Applications that Use C++Builder and the C++ Boost Libraries by David I – Boost is a set of open source C++ libraries that build on the ISO C++ programming language. In some cases, the Boost library functionality has become part of recent ISO C++ standards. RAD Studio allows you to install a subset of Boost that has been fully tested and preconfigured specifically for C++Builder. Use the GetIt Package Manager to install the Boost libraries for the Win32 classic C++ compiler, Win32 Clang-enhanced C++ compiler and Win64 Clang-enhanced compiler.
C++ developers often ask about ISO C++ language support in releases of Embarcadero C++Builder. This post includes links and information about the C++ compilers, Dinkumware Standard C++ libraries and Boost libraries that are included in C++Builder 10.4 Sydney Release 1.
David Millington, Product Manager for C++Builder keeps the Embarcadero C++Builder information updated on the C++ Reference compiler support page. On this page you can look at the different ISO C++ language releases to see what many compilers support in their compiler releases.
Dinkumware Standard Library
The Dinkumware Standard C++ Library is the implementation of the C++ Standard Library that C++Builder uses for applications on the 32-bit Windows, 64-bit Windows and macOS target platforms.
The libraries include containers such as vectors, lists, sets, maps, and bitsets. Dinkumware also includes algorithms for common operations, such as sorting a container or searching inside a container.
Dinkumware version 8.03a is available specifically for C++ application development on target platforms that support the Clang enhanced compilers. Dinkumware version 5.01 is provided to support the classic C++ compiler.
Note: C++Builder does not currently support the use of the Dinkumware Standard C++ Library on mobile platforms. On mobile platforms, the SDK’s standard library platform is used.
Boost Libraries
C++Builder supports different versions of the Boost libraries depending on the C++ compiler that you use to compile your application.
C++Builder Product Page – Native Apps that Perform. Build Windows C++ Apps 10x Faster with Less Code
C++Builder Product Editions – C++Builder is available in four editions – Professional, Enterprise, Architect and Community (free). C++Builder is also available as part of the RAD Studio development suite.
Desktop First UX Summit – Sept 16th & 17th, 2020
The FREE Desktop First UX Summit is your chance to learn from the best UI and UX industry experts and practitioners and take your desktop applications to the next level.
Move beyond the Mobile-First design of just stretching a small UI to fill a desktop screen. Learn how to take the most advantage of the most powerful platform and make your users more productive. Sponsored by Embarcadero’s RAD Studio 10.4 Sydney.
Here are the first two of many talks being given at the Desktop First UX Summit:
Boost is a set of open source C++ libraries that build on the ISO C++ programming language. In some cases, the Boost library functionality has become part of recent ISO C++ standards. RAD Studio allows you to install a subset of Boost that has been fully tested and preconfigured specifically for C++Builder. Use the GetIt Package Manager to install the Boost libraries for the Win32 classic C++ compiler, Win32 Clang-enhanced C++ compiler and Win64 Clang-enhanced compiler.
Boost libraries available in C++Builder’s GetItPackage Manager
boost::filesystem and std:filesystem VCL example
The ISO C++ std::filesystem evolved from the Boost filesystem library. The Filesystem library started in Boost, then became an ISO C++ Technical Specification and was finally merged into the ISO C++17 standard. The first example shows how to create a C++Builder VCL application using the Boost filesystem and the ISO C++ filesystem.
The VCL form contains two TButton, one TEdit and two TMemo components. The TEdit is used to set a path to files and directories on your hard drive. One button OnClick event handler will use the boost::filesystem functions to display the contents of the path. The other button OnCLick event handler will use the std::filesystem functions to display the contents of the same path. Why use both libraries? You may have an application and compiler than does not support the latest C++17 filesystem library standard. There are additional boost library versions available to support a wider range of platform filesystem operations.
VCL form for Boost and Std filesystem libraries application
C++Builder VCL application after using the boost and std filesystem library buttons
Filesystem VCL app mainunit.h:
//---------------------------------------------------------------------------
#ifndef MainUnitH
#define MainUnitH
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published: // IDE-managed Components
TButton *BoostButton;
TEdit *Edit1;
TMemo *Memo1;
TButton *Cpp17Button;
TMemo *Memo2;
void __fastcall BoostButtonClick(TObject *Sender);
void __fastcall Cpp17ButtonClick(TObject *Sender);
private: // User declarations
public: // User declarations
__fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif
Filesystem VCL App MainUnit.cpp:
//---------------------------------------------------------------------------
#include <vcl.h>
/*
https://en.cppreference.com/w/cpp/filesystem
The filesystem library was originally developed as boost.filesystem,
was published as the technical specification ISO/IEC TS 18822:2015,
and finally merged to ISO C++ as of C++17.
https://www.boost.org/doc/libs/1_70_0/libs/filesystem/doc/index.htm
*/
#include <boost/filesystem.hpp>
namespace Boostfs = boost::filesystem;
#include <filesystem>
namespace Cpp17fs = std::filesystem;
#pragma hdrstop
#include "MainUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::BoostButtonClick(TObject *Sender)
{
// Boost Filesystem verion
Memo1->Lines->Clear();
// use the Boost FileSystem to get directories and files using path in editbox
Boostfs::path directoryPath = Edit1->Text.c_str();
for (const auto& entry : Boostfs::directory_iterator(directoryPath)) {
Boostfs::path p = entry.path();
// test if the path is a file
if (is_regular_file(p)) {
int fsize = file_size(p);
std::string s = p.string() + " : size = ";
Memo1->Lines->Add(s.c_str() + IntToStr(fsize));
}
// test if the path is a directory
else if (is_directory(p)) { // is p a directory?
std::string s = p.string() + " : directory";
Memo1->Lines->Add(s.c_str());
}
// otherwise it is something else :)
else {
std::string s = p.string() + " not a file or directory";
Memo1->Lines->Add(p.c_str());
}
}
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Cpp17ButtonClick(TObject *Sender)
{
// C++17 FileSystem version
Memo2->Lines->Clear();
// use C++17 std FileSystem library to get directories given a path in the editbox
Cpp17fs::path directoryPath = Edit1->Text.c_str();
for (const auto& entry : Cpp17fs::directory_iterator(directoryPath)) {
Cpp17fs::path p = entry.path();
if (Cpp17fs::is_directory(p)) {
std::string s = p.string() + " : directory";
Memo2->Lines->Add(s.c_str());
}
else if (Cpp17fs::is_regular_file(p)) {
int fsize = Cpp17fs::file_size(p);
std::string s = p.string() + " : size = ";
Memo2->Lines->Add(s.c_str() + IntToStr(fsize));
}
else {
std::string s = p.string() + " not a file or directory";
Memo2->Lines->Add(p.c_str());
}
}
}
//---------------------------------------------------------------------------
boost::circular_buffer VCL example
The boost circular buffer (also known as a ring or cyclic buffer) library allows for the storing of data. The boost is designed to support fixed capacity storage. When the buffer is full, additional elements will overwrite existing elements at the front and back of the buffer (depending on the operations used).
The VCL form contains three TButton, one TSpinEdit and one TMemo components. One TButton OnClick event handler shows the contents of the circular buffer (originally populated by the Form’s OnShow event handler. The other two TButton OnClick event handlers use the boost circular buffer push_front and push_back public member functions.
Boost circular buffer C++Builder VCL form
C++Builder VCL form with Circular Buffer populated by OnShow event handler
Application showing contents of Circular Buffer after Add to front button is clicked
Application showing contents of Circular Buffer after Add to back button is clicked
C++Builder Product Page – Native Apps that Perform. Build Windows C++ Apps 10x Faster with Less Code C++Builder Product Editions – C++Builder is available in four editions – Professional, Enterprise, Architect and Community (free). C++Builder is also available as part of the RAD Studio development suite.
I have many favorite prebuilt components that are included with C++Builder10.4 Sydney. In this blog post I’ll show you how to create an RSS Feeds VCL (you can also use the same approach for a FireMonkey FMX) application using the XMLDocument, NetHTTPClient, NetHTTPRequest and WebBrowser components.
Start by creating a C++Builder VCL application. Set the form’s WindowState property to wsMaximized. Add a Panel, Button, ListBox (used to hold the list of RSS feed URLs to process) and a few labels and align them to the top of the form. Add Memo (to display the Feed XML), ListBox (to contain the title and URL for each article found in the feeds) and WebBrowser (to display the web page when you click on an item in the articles list box) components to the rest of the form.
The RSS Feed application’s main form.
To populate the Panel’s listbox, I use a text file, “FeedsList.txt”, which contains a number of RSS feed URLs. The panel listbox is populated in the Form’s OnShow event handler.
Clicking on the button will process all of the RSS feed URLs and add each article and URL item found into the list box of articles found.
The XMLDocument component has a DOMVendor property to select the DOM implementation to use for parsing and manipulating the XML document.
Clicking on an item in the articles list box uses the OnClick event handler to call the WebBrowser Navigate method for the selected article URL. In C++Builder 10.4 Sydney there is a new property added to the WebBrowser component that lets you choose which browser engine will be used on Windows. I’ve chosen the EdgeIfAvailable engine.
RSS Feeds Application Running with article selected and appearing in the Browser.
Finally here is the source code for the application:
//---------------------------------------------------------------------------
#include <vcl.h>
#include <fstream>
#pragma hdrstop
#include "MainFeedUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm2 *Form2;
//---------------------------------------------------------------------------
__fastcall TForm2::TForm2(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm2::ArticlesFoundListBoxClick(TObject *Sender)
{
// for the ListBox item clicked - get the URL and Browse to the article
LabelStatus->Caption = ArticlesFoundListBox->Items->Names[ArticlesFoundListBox->ItemIndex];
ArticleWebBrowser->Navigate(ArticlesFoundListBox->Items->Values[ArticlesFoundListBox->Items->Names[ArticlesFoundListBox->ItemIndex]]);
}
//---------------------------------------------------------------------------
void __fastcall TForm2::Button1Click(TObject *Sender)
{
// Find and save Title and URL for items found
std::ofstream fs (AnsiString(FormatDateTime("yyyy-mm-dd-hhnnss",Now())+"_RSSFound.txt").c_str());
fs << AnsiString("RSS Feed for: "+ NetHTTPRequest1->URL).c_str() << std::endl;
fs << AnsiString(FormatDateTime("dddd mmmm dd, yyyy @ hh:nn:ss",Now())).c_str() << std::endl;
fs << std::endl;
// Clear the Articles Found List Box to prepare for the title and URL of articles
ArticlesFoundListBox->Clear();
FeedsItemsCountLabel->Caption = "Items Found = 0";
// get all articles and URLs in all feeds
for (int i = 0; i < FeedsListBox->Count; i++) {
// Get the RSS feed URL string from the ListBox
NetHTTPRequest1->URL = FeedsListBox->Items->Strings[i];
UrlLabel->Caption = "Feed URL: "+NetHTTPRequest1->URL;
UrlLabel->Update();
// Use NetHTTPRequest Execute method to get the RSS Feed XML
UnicodeString FeedString = NetHTTPRequest1->Execute()->ContentAsString();
// copy the XML string to the Memo
MemoFeedXML->Lines->Clear();
MemoFeedXML->Lines->Text = FeedString;
MemoFeedXML->Update();
// load the RSS Feed XML into the XMLDocument
XMLDocument1->LoadFromXML(FeedString);
XMLDocument1->Active = True;
LabelStatus->Caption = "Processing RSS for "+NetHTTPRequest1->URL;
LabelStatus->Update();
// find the RSS feed channel node
_di_IXMLNode ChannelNode = XMLDocument1->DocumentElement->ChildNodes->FindNode ("channel");
// test to make sure the ChannelNote is found
if (ChannelNode != NULL) {
for (int I=0;I<ChannelNode->ChildNodes->Count;I++) {
// iterate through child nodes
_di_IXMLNode ItemNode = ChannelNode->ChildNodes->Get(I);
// if child node is an item then get the title, pubDate and URL
if (ItemNode->NodeName == "item") {
LabelStatus->Caption = "Processing Node " + IntToStr(I);
LabelStatus->Update();
UnicodeString title = ItemNode->ChildValues ["title"];
UnicodeString pubDate = ItemNode->ChildValues ["pubDate"];
// author := ItemNode.ChildValues ['author']; // could be nil
UnicodeString url = ItemNode->ChildValues ["link"];
// populate the articles found ListBox with the pair of title and URL
ArticlesFoundListBox->Items->AddPair(title,url);
ArticlesFoundListBox->Update();
FeedsItemsCountLabel->Caption = "Items Found = "+IntToStr(ArticlesFoundListBox->Count);
FeedsItemsCountLabel->Update();
// write the Title, pubDate and URL to the text file
fs << AnsiString(title).c_str() << std::endl;
fs << AnsiString(pubDate).c_str() << std::endl;
fs << AnsiString(url).c_str() << std::endl;
fs << std::endl;
}
}
}
}
fs << std::endl;
fs << AnsiString("Items Found = "+IntToStr(ArticlesFoundListBox->Count)).c_str() << std::endl;
fs << "end of file" << std::endl;
fs.close(); // close the text file
LabelStatus->Caption = "RSS Processing Done!";
UrlLabel->Caption = "";
}
//---------------------------------------------------------------------------
void __fastcall TForm2::FormShow(TObject *Sender)
{
// load RSS Feeds ListBox with the "FeedsList.txt" text file
// I put the text file in the same folder as the app .EXE file
FeedsListBox->Items->Clear();
FeedsListBox->Items->LoadFromFile("FeedsList.txt");
LabelStatus->Caption = "RSS Feed Urls Loaded = "+IntToStr(FeedsListBox->Count);
LabelStatus->Update();
}
//---------------------------------------------------------------------------
C++Builder Product Page – Native Apps that Perform. Build Windows C++ Apps 10x Faster with Less Code C++Builder Product Editions – C++Builder is available in four editions – Professional, Enterprise, Architect and Community (free). C++Builder is also available as part of the RAD Studio development suite.
Roberto V. Zicari interviewed Bjarne Stroustrup, the inventor of C++ programming language, back in 2007. Roberto again interviews Bjarne 13 years later.
In the interview, Bjarne talks about notable computer scientists that influenced his career and work. Bjarne also talks about why he designed the C++ language and why he started with the C language. Bjarne also talks about three guiding principles for the design of the C++ language: “Make the language simpler! Add these two essential features now!! Don’t break (any of) my code!!!”
ODBMS.ORG is designed to meet the fast-growing need for resources focusing on AI, Big Data, Data Science, Analytical Data Platforms, Scalable Cloud platforms, NewSQL databases, NoSQL datastores, In-Memory Databases, and new approaches to concurrency control.
About Roberto Zicari
Roberto is Full Professor of Database and Information Systems at Frankfurt University. He was for over 15 years the representative of the OMG in Europe. Previously, Roberto served as associate professor at Politecnico di Milano, Italy; Visiting scientist at IBM Almaden Research Center, USA, the University of California at Berkeley, USA; Visiting professor at EPFL in Lausanne, Switzerland, the National University of Mexico City, Mexico and the Copenhagen Business School, Danemark.
About Bjarne Stroustrup
Bjarne is a Technical Fellow and a Managing Director in the technology division of Morgan Stanley in New York City and a Visiting Professor in Computer Science at Columbia University. Bjarne designed and implemented the C++ programming language. To make C++ a stable and up-to-date base for real-world software development, Bjarne says “I have stuck with its ISO standards effort for almost 30 years (so far).”
