c++ - Calling a function name built with __LINE__ -


suppose, have built unique function body below code:

#define tokenpaste(x, y) x ## y #define tokenpaste2(x, y) tokenpaste(x, y) #define unique static void tokenpaste2(unique_, __line__)(void)

how can call function ?

macro definition taken from: creating c macro ## , __line__ (token concatenation positioning macro).

no. cannot. because cannot determine function name @ runtime. (i.e. either call unique_22 or unique_44. can call unique<22> or unique<44>)

so can use template solution instead. declare unique below:

template<unsigned int line> void unique ();

and #define macro this:

#define unique template<> unique<__line__>() {}

i advice use __counter__ instead of __line__ if compiler supports it. [note: means in line can call unique once , macro should expanded in global or namespace scope (not inside method).]


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