Deduce non-type template parameter

Posted by pezcode on Stack Overflow See other posts from Stack Overflow or by pezcode
Published on 2012-01-12T14:57:36Z Indexed on 2013/07/02 11:05 UTC
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Is it possible to deduce a non-type template parameter from a template function parameter?

Consider this simple template:

template <int N> constexpr int factorial()
{
        return N * factorial<N - 1>();
}

template <> constexpr int factorial<0>()
{
        return 1;
}

template <> constexpr int factorial<1>()
{
        return 1;
}

I would like to be able to change factorial so that I can alternatively call it like this:

factorial(5);

and let the compiler figure out the value of N at compile time. Is this possible? Maybe with some fancy C++11 addition?

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