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c++ - 委托(delegate)模板元编程的问题

转载 作者:行者123 更新时间:2023-11-28 07:37:22 25 4
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以下代码由另一位程序员改编自 Yingle Jia's code我必须将它移植到 Linux。它在 VS2010 中编译得很好,但是当我尝试在 Ubuntu 中使用 gcc 4.6.3 构建时,它在

处显示错误
template <class R ACF_DELEGATE_COMMA ACF_DELEGATE_TEMPLATE_PARAMS>
class Delegate<R (ACF_DELEGATE_TEMPLATE_ARGS)>

错误信息是:

../../../mySDK-master/include/abc/DelegateTemplate.h:45:1: error: pasting "," and "class" does not give a valid preprocessing token
../../../mySDK-master/include/abc/DelegateTemplate.h:46:1: error: pasting "," and "T" does not give a valid preprocessing token
../../../mySDK-master/include/abc/DelegateTemplate.h:74:1: error: pasting "," and "a" does not give a valid preprocessing token

第 45 和 46 行是我在上面粘贴的 DelegateTemplate.h 的两行代码。

Delegate.h

// Copyright (C) 2004-2005 Yingle Jia
//
// Permission to copy, use, modify, sell and distribute this software is
// granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied warranty,
// and with no claim as to its suitability for any purpose.
//
// AcfDelegate.h
//

#ifndef __Acf_Delegate__
#define __Acf_Delegate__

#ifndef __Acf_Corlib__
#include <stdexcept> // for std::runtime_error
#endif // #ifndef __Acf_Corlib__
#include <utility> // for std::pair

// Macros for template metaprogramming

#define ACF_JOIN(a, b) ACF_DO_JOIN(a, b)
#define ACF_DO_JOIN(a, b) ACF_DO_JOIN2(a, b)
#define ACF_DO_JOIN2(a, b) a##b

#define ACF_MAKE_PARAMS1_0(t)
#define ACF_MAKE_PARAMS1_1(t) t##1
#define ACF_MAKE_PARAMS1_2(t) t##1, ##t##2
#define ACF_MAKE_PARAMS1_3(t) t##1, ##t##2, ##t##3
#define ACF_MAKE_PARAMS1_4(t) t##1, ##t##2, ##t##3, ##t##4
#define ACF_MAKE_PARAMS1_5(t) t##1, ##t##2, ##t##3, ##t##4, ##t##5
#define ACF_MAKE_PARAMS1_6(t) t##1, ##t##2, ##t##3, ##t##4, ##t##5, ##t##6

#define ACF_MAKE_PARAMS2_0(t1, t2)
#define ACF_MAKE_PARAMS2_1(t1, t2) t1##1 t2##1
#define ACF_MAKE_PARAMS2_2(t1, t2) t1##1 t2##1, t1##2 t2##2
#define ACF_MAKE_PARAMS2_3(t1, t2) t1##1 t2##1, t1##2 t2##2, t1##3 t2##3
#define ACF_MAKE_PARAMS2_4(t1, t2) t1##1 t2##1, t1##2 t2##2, t1##3 t2##3, t1##4 t2##4
#define ACF_MAKE_PARAMS2_5(t1, t2) t1##1 t2##1, t1##2 t2##2, t1##3 t2##3, t1##4 t2##4, t1##5 t2##5
#define ACF_MAKE_PARAMS2_6(t1, t2) t1##1 t2##1, t1##2 t2##2, t1##3 t2##3, t1##4 t2##4, t1##5 t2##5, t1##6 t2##6

#define ACF_MAKE_PARAMS1(n, t) ACF_JOIN(ACF_MAKE_PARAMS1_, n) (t)
#define ACF_MAKE_PARAMS2(n, t1, t2) ACF_JOIN(ACF_MAKE_PARAMS2_, n) (t1, t2)

namespace CORE
{

#ifndef __Acf_Corlib__
class InvalidOperationException : public std::runtime_error
{
public:
InvalidOperationException() : std::runtime_error("Invalidate operation")
{
}
};
#endif // #ifndef __Acf_Corlib__

template <class TSignature>
class Delegate; // no body

}

// Specializations

#define ACF_DELEGATE_NUM_ARGS 0 // Delegate<R ()>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define ACF_DELEGATE_NUM_ARGS 1 // Delegate<R (T1)>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define ACF_DELEGATE_NUM_ARGS 2 // Delegate<R (T1, T2)>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define ACF_DELEGATE_NUM_ARGS 3 // Delegate<R (T1, T2, T3)>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define ACF_DELEGATE_NUM_ARGS 4 // Delegate<R (T1, T2, T3, T4)>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define ACF_DELEGATE_NUM_ARGS 5 // Delegate<R (T1, T2, T3, T4, T5)>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define ACF_DELEGATE_NUM_ARGS 6 // Delegate<R (T1, T2, T3, T4, T5, T6)>
#include "DelegateTemplate.h"
#undef ACF_DELEGATE_NUM_ARGS

#define N_INVOKE(DELEGATE,PARAMS) { if(DELEGATE) DELEGATE.Invoke PARAMS; }
#define N_EVENT_HANDLER(a) std::make_pair(this,&a);

#endif // #ifndef __Acf_Delegate__

和DelegateTemplate.h的一小部分

// Copyright (C) 2004-2005 Yingle Jia
//
// Permission to copy, use, modify, sell and distribute this software is
// granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied warranty,
// and with no claim as to its suitability for any purpose.
//
// AcfDelegateTemplate.h
//
// Note: this header is a header template and must NOT have multiple-inclusion
// protection.

#define ACF_DELEGATE_TEMPLATE_PARAMS ACF_MAKE_PARAMS1(ACF_DELEGATE_NUM_ARGS, class T)
// class T0, class T1, class T2, ...
#define ACF_DELEGATE_TEMPLATE_ARGS ACF_MAKE_PARAMS1(ACF_DELEGATE_NUM_ARGS, T)
// T0, T1, T2, ...
#define ACF_DELEGATE_FUNCTION_PARAMS ACF_MAKE_PARAMS2(ACF_DELEGATE_NUM_ARGS, T, a)
// T0 a0, T1 a1, T2 a2, ...
#define ACF_DELEGATE_FUNCTION_ARGS ACF_MAKE_PARAMS1(ACF_DELEGATE_NUM_ARGS, a)
// a0, a1, a2, ...

//// Comma if nonzero number of arguments
#if ACF_DELEGATE_NUM_ARGS == 0
#define ACF_DELEGATE_COMMA
#else
#define ACF_DELEGATE_COMMA ,
#endif

namespace CORE
{

//-------------------------------------------------------------------------
// class Delegate<R (T1, T2, ..., TN)>

template <class R ACF_DELEGATE_COMMA ACF_DELEGATE_TEMPLATE_PARAMS>
class Delegate<R (ACF_DELEGATE_TEMPLATE_ARGS)>
{
// Declarations
private:
class DelegateImplBase
{
// Fields
public:
DelegateImplBase* Previous; // singly-linked list

// Constructor/Destructor
protected:
DelegateImplBase() : Previous(NULL) { }
DelegateImplBase(const DelegateImplBase& other) : Previous(NULL) { }
public:
virtual ~DelegateImplBase() { }

// Methods
public:
virtual DelegateImplBase* Clone() const = 0;
virtual R Invoke(ACF_DELEGATE_FUNCTION_PARAMS) const = 0;
};

是不是因为gcc不支持Template Metaprogramming?我检查了它是否是因为可变参数模板,但这应该在 gcc 4.3 本身中得到修复。如果您能帮助解决此错误,我们将不胜感激。

最佳答案

已解决。我经历了this page并了解应该如何使用 token 粘贴运算符:

事实证明,Visual Studio 忽略了一些额外的 ## 运算符,但 gcc 没有。我更改的行是:

#define ACF_MAKE_PARAMS1_0(t)
#define ACF_MAKE_PARAMS1_1(t) t ## 1
#define ACF_MAKE_PARAMS1_2(t) t ## 1, t ## 2
#define ACF_MAKE_PARAMS1_3(t) t ## 1, t ## 2, t ## 3
#define ACF_MAKE_PARAMS1_4(t) t ## 1, t ## 2, t ## 3, t ## 4
#define ACF_MAKE_PARAMS1_5(t) t ## 1, t ## 2, t ## 3, t ## 4, t ## 5
#define ACF_MAKE_PARAMS1_6(t) t ## 1, t ## 2, t ## 3, t ## 4, t ## 5, t ## 6

前面的行有类似 ##t##2 的内容,这导致了错误。我将其更改为 t##2 并且成功了!荣耀哈利路亚! :-) 就这样结束了我对模板元编程的折磨。

关于c++ - 委托(delegate)模板元编程的问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16515546/

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