Question

The following code prints out the string “T” not the actual typename when the templated function is called. Is there a way to get the real typename without adding anything to the types being templated?

#define stringify(a) #a
#define tostring(a) stringify(a)

template <typename T>
void function_foo(T a, T b)
{
    cout << tostring(T) << endl;
    ...
}

Answer 1

Templates don’t work like that. In your template T specifies a type, and not a sequence of tokens:

typedef int lolztype;
typedef int lulztype;

function_foo<lolztype>(0, 0);
function_foo<lulztype>(0, 0); // calls the *same* template

There is no way to get lolztype or lulztype respectively. What you could try is using typeid(T).name(), but that isn’t very helpful because it isn’t required to be human readable and not even required to be distinct for each type.

You could try using geordi’s file type_strings.hpp, which can print out a human readable string when compiled with GCC.