Preprocessor and template arguments or conditional compilation of piece of code

Question

How I can compile template function with pre-processor condition? Like that (but it is not working):

template 
void f()
{
    #if (var == tru         


        

Answer 1

If you need to generate different code paths with template parameter, you can just simply use if or other C++ statement:

template 
void f()
{
    if (var == true) ｛
        // ...
    ｝
｝

Compiler can optimize it and generate code that doesn't contain such branches.

A little drawback is that some compiler (e.g. Msvc) will generate warnings for conditions which is always constant.