template specialization according to sizeof type

Question

I would like to provide a templated function, that varies its implementation (->specialization) according to the sizeof the template type.

Something similar to this (omi

Answer 1

Just for the sake of demonstrating enable_if in action, since you spoke about it:

template 
typename boost::enable_if_c< sizeof(T) == 2, T >::type
swapIt(T& rhs) { return _byteswap_short(rhs); }

template 
typename boost::enable_if_c< sizeof(T) == 4, T >::type
swapIt(T& rhs) { return _byteswap_long(rhs); }

etc...

And of course, instead of throwing, there is just no implementation if the type doesn't meet any of the requirement and thus you have a compile time error.

Two notes:

• Use of typename and ::type are mandatory
• I used enable_if_c because my expression evaluates to a boolean value directly, whereas enable_if requires a type containing a ::value member which is a boolean.