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C++: auto-cast a class?

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Started by silverphyre673 November 12, 2005 03:01 PM

9 comments, last by rip-off 18 years, 5 months ago

silverphyre673

454

Author

November 12, 2005 03:01 PM

I have a wrapper for the float type, called Scalar, which I'm using while building my physics engine. Is there any way that I could automatically cast the Scalar class into a float? For example, currently, this would give an error:


void DoSomething(float f)
{
    //some operation on f
}

void Foo
{
    Scalar x = 50.0f;
    DoSomething(x); //ERROR!  Cannot convert 'scalar' to 'float'
}

I could just do something like this: DoSomething(x.Value()); Where x.Value() returns the floating-point value of "x", but I would rather not. It doesn't look pretty [grin] If you have a better solution, please let me know. Thanks!

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Telastyn

3,778

November 12, 2005 03:05 PM

conversion operators I believe.

IIRC:

struct   scalar{     float     x;     operator  float(){return(x);}};

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bakery2k1

712

November 12, 2005 03:07 PM

Give your scalar class an "operator float":

class Scalar{public:operator float() const{ return value; }float value;};

Note that these implicit conversions are generally considered poor style - what does your Scalar class provide that a pure float does not?

rip-off

11,000

November 12, 2005 03:09 PM

Quote:Original post by bakery2k1
Give your scalar class an "operator float":

*** Source Snippet Removed ***

Note that these implicit conversions are generally considered poor style - what does your Scalar class provide that a pure float does not?

the ability to be changed to a double at a single point in the program,
should the need arise

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