CODEWITHSUNDEEP
c++templates
Eagle
Eagle

Reputation: 3486

using typedef with template

The code below taken from here (and modified a bit) produce the following error message using g++ compiler: error: template declaration of 'typedef' /RangeChecks.hpp:145:12: error: 'IsInRange' does not name a type

here are the relevant parts from my RangeChecks.hpp file:

class GreaterEqual
{
  public:
     template <class T>
     static bool Compare (const T& value, const T& threshold)
     {
        return !(value < threshold); /* value >= threshold */
     }
};

class LessEqual
{
  public:
     template <class T>
     static bool Compare (const T& value, const T& threshold)
     {
        return !(value > threshold); /* value <= threshold */
     }
};

template <class L, class R, class T>
bool IsInRange (const T& value, const T& min, const T& max)
{
     return L::template Compare<T> (value, min) && R::template Compare<T> (value, max);
}

typedef IsInRange< GreaterEqual , LessEqual > isInClosedRange;

I searched over the internet for an answer and there are simular things but non of them, that i found, solved my problem.

Upvotes: 0

Views: 78

Answers (2)

CAdaker
CAdaker

Reputation: 14721

IsInRange is a function, not a type. The easiest way to do what you want to do is to write a wrapper:

template<class T>
bool isInClosedRange(const T& value, const T& min, const T& max) {
    return IsInRange<T, GreaterEqual, LessEqual>(value, min, max);
}

Upvotes: 4

user1804599
user1804599

Reputation:

IsInRange is a function template, not a class template, so an instantiation of it is not a type, so you can't create a typedef for it.

Upvotes: 3

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