Re: [Boost-users] Constant floats

Are function calls allowed to default initialize a construction parameter? Does the compiler turn the function into a constant? How does that work? I wasn't aware you could do this... On Dec 11, 2007 8:02 PM, Stjepan Rajko wrote:

On Dec 11, 2007 1:03 PM, Robert Dailey wrote:

...

template< typename T > struct default_alpha;

template<> struct default_alpha<float> { static const float value = 1.0f; // Note that this is not legal. I'm simply just presenting pseudo code.

};

template<> struct default_alpha<unsigned char> { static const unsigned char value = 255; };

template< typename T > class Color { Color( T r, T g, T b, T a = default_alpha<T>::value ); };

So why not use Jeff Flinn's suggestion:

template< typename T > struct default_alpha;

template<> struct default_alpha<float> { static float value() { return 1.0f; } };

template<> struct default_alpha<unsigned char> { static unsigned char value() { return 255; } };

template< typename T > class Color { public: Color( T r, T g, T b, T a = default_alpha<T>::value() ); };

...?

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