C++语法游戏 : 模仿C#的 using(...){}

王朝vc·作者佚名  2006-01-08
窄屏简体版  字體: |||超大  

游戏而已,,可以用来锻炼脑筋。。~~

//using.h

#pragma once

//for IUnknown

#include "atlbase.h"

#define USING_SCOPE_ASSERT(x) ATLASSERT(x);

#define USING_SCOPE_INLINE inline

#define Using(expression) if(UsingScope UsingScope_LocalVar=(expression))

class UsingScope

{

class Container

{

public:

virtual ~Container()

{

}

};

Container* pc;

public:

USING_SCOPE_INLINE operator bool ()

{

return true;

}

USING_SCOPE_INLINE ~UsingScope()

{

delete pc;

}

template

class SimplePointerContainer:public Container

{

T* p;

public:

SimplePointerContainer(T* p)

{

USING_SCOPE_ASSERT(p!=NULL);

this-p=p;

}

virtual ~SimplePointerContainer()

{

delete p;

}

};

template

USING_SCOPE_INLINE UsingScope(T* p)

{

pc=new SimplePointerContainer(p);

}

class IUnknownContainer:public Container

{

IUnknown* punk;

public:

IUnknownContainer(IUnknown* punk)

{

USING_SCOPE_ASSERT(punk!=NULL);

this-punk=punk;

}

virtual ~IUnknownContainer()

{

punk-Release();

}

};

USING_SCOPE_INLINE UsingScope(IUnknown* punk)

{

pc=new IUnknownContainer(punk);

}

class BSTRContainer:public Container

{

BSTR bstr;

public:

BSTRContainer(BSTR bstr)

{

USING_SCOPE_ASSERT(bstr!=NULL);

this-bstr=bstr;

}

virtual ~BSTRContainer()

{

SysFreeString(bstr);

}

};

USING_SCOPE_INLINE UsingScope(BSTR bstr)

{

pc=new BSTRContainer(bstr);

}

//vc7 m 可以为System::IDisposable* 添加 .Dispose() 的调用

//以支持所有的dotnet System::IDisposable的实现者

};

//usingT.h

#include "Using.h"

#define UsingT(type,varname,expression) if(UsingScopeT varname=(expression))

template

class UsingScopeT

{

template

class Container

{

public:

T* p;

Container(T* p)

{

USING_SCOPE_ASSERT(p!=NULL);

this-p=p;

}

virtual ~Container(){}

};

Container* pc;

public:

USING_SCOPE_INLINE operator bool ()

{

return true;

}

USING_SCOPE_INLINE T* operator - ()

{

return (pc-p);

}

USING_SCOPE_INLINE operator T*() const

{

return (T*)(pc-p);

}

USING_SCOPE_INLINE T& operator*() const

{

return *(pc-p);

}

USING_SCOPE_INLINE T** operator&()

{

return &(pc-p);

}

USING_SCOPE_INLINE bool operator==(T* pT) const

{

return (pc-p) == pT;

}

USING_SCOPE_INLINE ~UsingScopeT()

{

delete pc;

}

template

class SimplePointerContainer:public Container

{

public:

SimplePointerContainer(T* p):Container(p)

{

}

virtual ~SimplePointerContainer()

{

delete p;

}

};

template

USING_SCOPE_INLINE UsingScopeT(T* p)

{

pc=new SimplePointerContainer(p);

}

class IUnknownContainer:public Container

{

public:

IUnknownContainer(IUnknown* punk):Container(punk)

{

}

virtual ~IUnknownContainer()

{

p-Release();

}

};

USING_SCOPE_INLINE UsingScopeT(IUnknown* punk)

{

pc=new IUnknownContainer(punk);

}

class BSTRContainer:public Container

{

public:

BSTRContainer(BSTR bstr):Container(bstr)

{

}

virtual ~BSTRContainer()

{

SysFreeString(p);

}

};

USING_SCOPE_INLINE UsingScopeT(BSTR bstr)

{

pc=new BSTRContainer(bstr);

}

//vc7 m 可以为System::IDisposable* 添加 .Dispose() 的调用

//以支持所有的dotnet System::IDisposable的实现者

};

//Using.Cpp

// Using.cpp : Defines the entry point for the console application.

//

#include "stdafx.h"

#include "atlbase.h"

#include "Using.h"

#include "UsingT.h"

class ClassA

{

public:

ClassA()

{

_tprintf(_T("ClassA()\n"));

}

virtual ~ClassA()

{

_tprintf(_T("~ClassA()\n"));

}

virtual void Write()

{

_tprintf(_T("ClassA::Write\n"));

}

};

class ClassB:public ClassA

{

public:

virtual void Write()

{

_tprintf(_T("ClassB::Write\n"));

}

};

ClassA* CreateClassA()

{

return new ClassB();

}

IUnknown* ReturnUnknown()

{

HRESULT hres;

IUnknown* p;

CLSID cid;

hres=CLSIDFromProgID(L"JScript",&cid);

hres=CoGetClassObject(cid,CLSCTX_INPROC_SERVER,NULL,IID_IClassFactory,(void**)&p);

return p;

}

void DoIt()

{

CoInitialize(NULL);

IUnknown* punk;

Using(punk=ReturnUnknown())

{

ClassA* pa;

Using(pa=CreateClassA())

{

_tprintf(_T("DoWork\n"));

pa-Write();

}

}

UsingT(ClassB,pb,new ClassB())

{

pb-Write();

ClassA* pa=pb;

if(pa==pb)

pa-Write();

}

UsingT(IUnknown,p,ReturnUnknown())

{

//p-..

}

CoUninitialize();

}

int main(int argc, char* argv[])

{

DoIt();

return 0;

}

 
 
 
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