Disambiguate template specialization between map-like and vector-like containers

Question

template struct Printer;

// I want this to match std::vector (and similar linear containers) 
template class T, clas         


        

Answer 1

The problem here is that

template  T

and

template  TM

both match any template classes that have at least 2 template parameters which is the case in both your examples. One thing you can do is to make both template parameter lists more specific, like for example:

template 
struct Printer;

template  class C, template  class A, typename T>
struct Printer< C> > {
    ...
};

template  class C, template  class Comp, template  class A, typename K, typename T>
struct Printer< C, A>> > {
    ...
};

You can see it working for std::vector and std::map here: http://coliru.stacked-crooked.com/a/7f6b8546b1ab5ba9

Another possibility is to use SFINAE (actually I'd recommend using it in both scenarios):

template class T, class TV, class... TS, class = typename std::enable_if::value>::type> 
struct Printer> { ... };

template class TM, class TK, class TV, typename... TS, class = typename std::enable_if::value>::type> 
struct Printer> { ... }

Edit: Oups, just read in the comments you wanted to match something 'std::vector'-like, not specifically std::vector. The first method however should at least differentiate between std::vector and std::map. If you want to write algorithms for containers with different ways to iterate over, why not write your functions for iterators and differentiate between those?

Edit2: The code before was miserably wrong. However it works now.