I like using SFINAE to check boolean conditions. template<int I> void div(char(*)[I % 2 == 0] = 0) { /* this is taken when I is even */ } template<int I> void div(char(*)[I % 2 == 1] = 0) { /* this is taken when I is odd */ } It can be quite useful. … Read more
Here’s a possible implementation relying on C++11 features. It correctly detects the function even if it’s inherited (unlike the solution in the accepted answer, as Mike Kinghan observes in his answer). The function this snippet tests for is called serialize: #include <type_traits> // Primary template with a static assertion // for a meaningful error message … Read more
1. Primary Class Template When you write has_member<A>::value, the compiler looks up the name has_member and finds the primary class template, that is, this declaration: template< class , class = void > struct has_member; (In the OP, that’s written as a definition.) The template argument list <A> is compared to the template parameter list of … Read more
Put the hack in the template parameters. The enable_if on template parameter approach has at least two advantages over the others: readability: the enable_if use and the return/argument types are not merged together into one messy chunk of typename disambiguators and nested type accesses; even though the clutter of the disambiguator and nested type can … Read more
What you need to do is have the preprocessor generate reflection data about the fields. This data can be stored as nested classes. First, to make it easier and cleaner to write it in the preprocessor we will use typed expression. A typed expression is just an expression that puts the type in parenthesis. So … Read more
Yes, with SFINAE you can check if a given class does provide a certain method. Here’s the working code: #include <iostream> struct Hello { int helloworld() { return 0; } }; struct Generic {}; // SFINAE test template <typename T> class has_helloworld { typedef char one; struct two { char x[2]; }; template <typename C> … Read more