如何将多参数模板传递到宏? [英] How to pass multi-argument templates to macros?
本文介绍了如何将多参数模板传递到宏?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
说我有这样的宏:
#define SET_TYPE_NAME(TYPE, NAME) \
template<typename T> \
std::string name(); \
\
template<> \
std::string name<TYPE>() { \
return NAME; \
}
如果我传递的模板有更多因为< int,int>
中的逗号被解释为将宏参数分开,而不是模板参数。
This won't work if I pass it a template that has more than one parameter, because the comma in the <int, int>
is interpreted as separating the macro arguments, not the template arguments.
SET_TYPE_NAME(std::map<int, int>, "TheMap")
// Error: macro expects two arguments, three given
这个问题似乎可以这样解决:
This problem seems to be solved by doing this:
SET_TYPE_NAME((std::map<int, int>), "TheMap")
但现在出现了另一个问题,我真的没有想到:
But now another problem arises, one that I really did not expect:
template<>
std::string name<(std::map<int, int>)>()
// template argument 1 is invalid
似乎额外的括号使模板参数无效。有什么办法吗?
It seems that the extra parentheses make the template argument invalid. Is there any way around this?
推荐答案
除了 typedef
切换参数的顺序并使用可变宏(需要C99或C ++ 11兼容的编译器):
Besides typedef
, you could switch the order of the arguments and use variadic macros (requires C99 or C++11-compatible compiler):
#define SET_TYPE_NAME(NAME, ...) \
template<typename T> \
std::string name(); \
\
template<> \
std::string name<__VA_ARGS__>() { \
return NAME; \
}
...
SET_TYPE_NAME("TheMap", std::map<int, int>)
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