Templates and delegates trouble
Lars Kyllingstad
public at kyllingen.NOSPAMnet
Tue Oct 7 07:18:15 PDT 2008
Hello,
I want to make a function (named 'call' in the example below) that calls
another function (F). I want to allow F to be an ordinary function, a
delegate, or a functor. I've been able to make it work with functions
and functors, but not with delegates. Any tips would be greatly appreciated.
I have defined 'call' like this:
T call(alias F, T=real)(T arg)
{
return F(arg);
}
I can now do like this:
call!(sqrt)(4.0);
or
class Sqrt
{
real opCall(real x) { return sqrt(x); }
}
auto sqrt = new Sqrt;
call!(sqrt)(4.0);
Both of these examples compile and the function returns 2.0 as expected.
I can not, however, do this:
class Sqrt
{
real eval(real x) { return sqrt(x); }
}
auto sqrt = new Sqrt;
call!(sqrt.eval)(4.0);
To this, the compiler (GDC) says:
Error: need 'this' to access member eval
So it would seem that even though eval is a method of the Sqrt class, F
aliases it as a function pointer. Is there any way of making this work?
-Lars
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