GerixSoft

Windows API functions are declared in structured programming style.

For example consider classical example of using critical sections:

procedure Test;
var 
  CS: TCriticalSection;
begin
  InitializeCriticalSection(CS);
  try
    EnterCriticalSection(CS);
    try
      //somecode
    finally
      LeaveCriticalSection(CS);
    end;
  finally
    DeleteCriticalSection(CS);
  end;
end;

Now consider the example rewritten in object-oriented Windows API:

procedure Test;
var
  NewCS: TNewCriticalSection;
begin
  NewCS.Initialize;
  try
    NewCS.Enter;
    try
      //somecode
    finally
      NewCS.Leave;
    end;
  finally
    NewCS.Delete;
  end;
end;

Bespoke the code is easier to read, the benefit is CodeInsight works nicely — type "NewCS." and press Control+Space…

Below unit implements new object-oriented Windows API:

unit NewWindows;

interface

uses Windows;

{$HINTS OFF}
type
  TNewCriticalSection = object
  private
    FOldCriticalSection: TRTLCriticalSection;
  public
    procedure Initialize; stdcall;
    procedure Delete; stdcall;
    procedure Enter; stdcall;
    procedure Leave; stdcall;
  end;
{$HINTS ON}
  
implementation

procedure TNewCriticalSection.Initialize; 
    external kernel32 name 'InitializeCriticalSection';
procedure TNewCriticalSection.Delete; 
    external kernel32 name 'DeleteCriticalSection';
procedure TNewCriticalSection.Enter; 
    external kernel32 name 'EnterCriticalSection';
procedure TNewCriticalSection.Leave; 
    external kernel32 name 'LeaveCriticalSection';

end. 

The trick is that Delphi object types are passed by value, hence when calling TNewCriticalSection.Initialize method, FOldCriticalSection field is occupying on the stack the same place argument of InitializeCriticalSection would do. Thus we can declare implementation of TNewCriticalSection.Initialize as external from kernel32.dll.