模板上的宏
不确定我想做的事情是否不好，但这是我的问题： 我有一些模板函数，例如
std::vector<T> operator - (const std::vector<T>& data1, const std::vector<T>& data2);
std::vector<T> operator * (const std::vector<T>& data1, const std::vector<T>& data2);
std::vector<T> operator & (const std::vector<T>& data1, const std::vector<T>& data2);
......等等。除了运算符之外，所有这些函数都具有完全相同的定义，所以我试图编写这样的宏
#define _BINARY_OP_ON_DATASET (OP_TYPE)
template <typename T> \
std::vector<T> operator OP_TYPE (const std::vector<T>& data1, const std::vector<T>& data2)\
{\
std::vector<T> result;\
result.push_back(data1.begin().val OP_TYPE data1.begin().val)/*sample implementation*/\
return result;\
}
_BINARY_OP_ON_DATASET (&)
_BINARY_OP_ON_DATASET (+)
，但我得到了一堆错误
Error 1 error C2833: 'operator OP_TYPE' is not a recognized operator or type
Error 2 error C2988: unrecognizable template declaration/definition
Error 3 error C2059: syntax error : 'newline'
Error 5 error C2143: syntax error : missing ';' before '<'
Error 6 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
......等等 谁能看出这有什么问题吗？
感谢您的任何帮助。
简历
Not sure if what am trying to do is bad but here's my question:
I have a some template functions like
std::vector<T> operator - (const std::vector<T>& data1, const std::vector<T>& data2);
std::vector<T> operator * (const std::vector<T>& data1, const std::vector<T>& data2);
std::vector<T> operator & (const std::vector<T>& data1, const std::vector<T>& data2);
....and so on. All of these functions have exactly the same definition except for the operator, so I was trying to write a macro like this
#define _BINARY_OP_ON_DATASET (OP_TYPE)
template <typename T> \
std::vector<T> operator OP_TYPE (const std::vector<T>& data1, const std::vector<T>& data2)\
{\
std::vector<T> result;\
result.push_back(data1.begin().val OP_TYPE data1.begin().val)/*sample implementation*/\
return result;\
}
_BINARY_OP_ON_DATASET (&)
_BINARY_OP_ON_DATASET (+)
And I get a bunch of errors
Error 1 error C2833: 'operator OP_TYPE' is not a recognized operator or type
Error 2 error C2988: unrecognizable template declaration/definition
Error 3 error C2059: syntax error : 'newline'
Error 5 error C2143: syntax error : missing ';' before '<'
Error 6 error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
...and more
Can anyone see whats the problem with this?
Thanks for any help.
CV
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评论（4）
宏参数列表之前没有空格！
No space before the macro argument list!
宏参数列表之前有一个无效的空格，并且错过了后面的换行符的转义：
You have an invalid space before the macro argument list and missed escaping the newline after it:
删除宏名称与其参数之间的空格。
将
\添加到模板的第一行删除小错误，例如您在函数体第二行中忘记的
;并且编译良好！
Remove the space between the macro name and it's arguments.
Add
\to the first line of your templateRemove the minor errors, such as the
;you forgot in the second line of your function bodyAnd it compiles well!
我认为重复定义比宏定义更简单:)有时重复自己比寻求更高的打字效率更好。
I think repeating the definition will be simpler than macro-fying them :) Sometimes it's just better to repeat yourself than to eek out more typing efficiency.