D Programming Language 1.0

Last update Sun Dec 30 20:34:43 2012

D for Win32

This describes the D implementation for 32 bit Windows systems. Naturally, Windows specific D features are not portable to other platforms.

Instead of the:

#include <windows.h>

of C, in D there is:

import std.c.windows.windows;

Calling Conventions

In C, the Windows API calling conventions are __stdcall. In D, it is simply:

extern (Windows)
	/* ... function declarations ... */

The Windows linkage attribute sets both the calling convention and the name mangling scheme to be compatible with Windows.

For functions that in C would be __declspec(dllimport) or __declspec(dllexport), use the export attribute:

export void func(int foo);

If no function body is given, it's imported. If a function body is given, it's exported.

Windows Executables

Windows GUI applications can be written with D. A sample such can be found in \dmd\samples\d\winsamp.d

These are required:

  1. Instead of a main function serving as the entry point, a WinMain function is needed.
  2. WinMain must follow this form:
    import std.c.windows.windows;
    extern (C) void gc_init();
    extern (C) void gc_term();
    extern (C) void _minit();
    extern (C) void _moduleCtor();
    extern (C) void _moduleDtor();
    extern (C) void _moduleUnitTests();
    extern (Windows)
    int WinMain(HINSTANCE hInstance,
    	HINSTANCE hPrevInstance,
    	LPSTR lpCmdLine,
    	int nCmdShow)
        int result;
        gc_init();			// initialize garbage collector
        _minit();			// initialize module constructor table
    	_moduleCtor();		// call module constructors
    	_moduleUnitTests();	// run unit tests (optional)
    	result = myWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
    	_moduleDtor();		// call module destructors
        catch (Object o)		// catch any uncaught exceptions
    	MessageBoxA(null, cast(char *)o.toString(), "Error",
    	result = 0;		// failed
        gc_term();			// run finalizers; terminate garbage collector
        return result;
    int myWinMain(HINSTANCE hInstance,
    	HINSTANCE hPrevInstance,
    	LPSTR lpCmdLine,
    	int nCmdShow)
        /* ... insert user code here ... */
    The myWinMain() function is where the user code goes, the rest of WinMain is boilerplate to initialize and shut down the D runtime system.
  3. A .def (Module Definition File) with at least the following two lines in it:
    Without those, Win32 will open a text console window whenever the application is run.
  4. The presence of WinMain() is recognized by the compiler causing it to emit a reference to __acrtused_dll and the phobos.lib runtime library.

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