Perform different methods based on template variable type
c++, templates, typeid, types
Solution
Use regular function overloading instead:
template <class T>
struct Jam
{
Jam(std::string* var)
{
*var = "Hello!";
}
Jam(int* var)
{
*var = 25;
}
};
unless you want to specialize on the type `T` used to instantiate `Jam`. In that case you would do:
template<>
struct Jam<std::string>
{
Jam(std::string* var)
{
*var = "Hello!";
}
};
template<>
struct Jam<int>
{
Jam(int* var)
{
*var = 25;
}
};
template<typename T>
struct Jam
{
Jam(T* var)
{
// every other type
}
};
Problem
Is there a way to determine the type of variable passed to a template and call a function based on if it's an `int` or `std::string` etc...? For example ``` template <class T> struct Jam { Jam(T *var) { if (typeid(var) == typeid(std::string*) *var = "Hello!"; else if (typeid(var) == typeid(int*) *var = 25; } }; ``` When I try to use that code, i get an error `invalid conversion from const char* to int`. I suspect this is because the compiler "expands" the template into separate functions and when I specified a new instance of the structure `throw Jam<std::string>(&setme);` it detected the `var* = 25` statement and refused to compile. Is there a proper way to do this? Maybe with macro guards? Thanks.