DELPHI是怎么实现跨平台的？

DELPHI是怎么实现跨平台的？

首先跨平台必须要兼容原来的语法，以线程的临界区对象为例：

TCriticalSection = class(TSynchroObject)

{$IFDEF POSIX}

private type

TCritSec = record

FSync: TObject;

procedure Initialize; inline;

procedure Free; inline;

procedure Enter; inline;

procedure Leave; inline;

function TryEnter: Boolean; inline;

end;

{$ENDIF POSIX}

protected

{$IFDEF MSWINDOWS}

FSection: TRTLCriticalSection;

{$ENDIF MSWINDOWS}

{$IFDEF POSIX}

FSection: TCritSec;

{$ENDIF POSIX}

public

constructor Create;

destructor Destroy; override;

procedure Acquire; override;

procedure Release; override;

function TryEnter: Boolean;

procedure Enter; inline;

procedure Leave; inline;

end;

可以看出，已经不单是原来的从WINDOWS OS临界封装，通过{$IFDEF POSIX}跨平台编译开关，增加了跨平台的封装。

下面再以线程类TThread为例：

TThread = class

private type

PSynchronizeRecord = ^TSynchronizeRecord;

TSynchronizeRecord = record

FThread: TObject;

FMethod: TThreadMethod;

FProcedure: TThreadProcedure;

FSynchronizeException: TObject;

end;

private class var

FProcessorCount: Integer;

private

FThreadID: TThreadID;

{$IF Defined(MSWINDOWS)}

FHandle: THandle platform;

{$ELSEIF Defined(POSIX)}

FCreateSuspendedMutex: pthread_mutex_t;

FInitialSuspendDone: Boolean;

{$ENDIF POSIX}

FStarted: Boolean;

FCreateSuspended: Boolean;

FTerminated: Boolean;

FSuspended: Boolean;

FFreeOnTerminate: Boolean;

FFinished: Boolean;

FReturnValue: Integer;

。。。。。。

也和临界区类一样用跨平台编译开关封装了跨平台代码进来。

从上面的2个例子可以看出，DELPHI为了跨平台，对RTL进行了艰苦卓绝的巨大修改，这个工程无疑是浩大的。