"structure constants" C++

[Bjarne Stroustrup]

Karl W. Z. Heuer writes:

> BMS-AT!stuart writes:
> >I would like to see "structure constants" which would allow assignment to
> >aggregate types.
> >       complex z;
> >       z = { a+1, exp(b) };
> >       foo( (complex) { a, b } );
> 
> The problem, as your last example points out, is that the notation "{...}"
> doesn't distinguish between different structure types.  I suppose the cast
> notation is workable, but kinda ugly.

Or in C++:

#include <complex.h>

void foo(complex);

void f() {
	double a,b;
	complex z;
	z = complex(a+1,exp(b));
	foo( complex(a,b) );
}

> >Of course any of these could be coded by assigning each member in turn.
> 
> No, the last example requires assigning each member to a temporary, and then
> passing that temporary as an argument.

However, a clever compiler might use the calling stack as the temporary, but that
is tricky (C++ doesn't attempt that feat).