Re: Templates: howto return T or vector<T> from one template
On 1/29/2013 7:34 AM, Marco Nawijn wrote:
I have a short question regarding the use of templates.
I have a template definition like the following:
template <typename T, uint64_t N=1>
T func(const stream &s)
{
// code..
}
Now, depending on whether N=1 or N>1 I would like to
return a variable of type T itself, or a vector<T>.
Is this possible with one template, or should I just
create a second template? If it is possible, how
should the return value of the function be specified?
It's better to wrap it into a class template, so you can actually
partially specialize it.
template<class T>
std::vector<T> func_N(const stream& s, uint64_t N) { ... }
teplate<class T>
T func_1(const stream& s) { ... } // case where N = 1
template<class T, uint64_t N>
struct func_helper {
typename std::vector<T> ret_t;
ret_t call(const stream& s) { return func_N(s, N); }
};
template<class T>
struct func_helper<T, 1> {
typename T ret_t;
ret_t call(const stream& s) { return func_1(s); }
};
So, in the call where you try to use your 'func' do this instead:
... = func_helper<myT, myN>::call(mystream);
Victor
V
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