On Tuesday, 5 February 2013 at 16:37:41 UTC, Nick Treleaven wrote:
On 05/02/2013 16:17, Nick Treleaven wrote:
On 03/02/2013 13:22, bearophile wrote:
Era Scarecrow:
On Sunday, 3 February 2013 at 09:11:59 UTC, Namespace wrote:
Sure, but alloca has the same ugly interface as malloc. :/
You mean that you have to specify how many raw bytes you
want, then
cast it to what you need? I never thought alloca or malloc
were that
ugly.
The interface of alloca() is bug-prone. And it's not handy if
you want
to create a 2D or nD array on the stack :-) In bugzilla there
is a
preliminary request for better and less bug-prone VLAs for D.
^ I know you're aware of this, but maybe others might not know
the
default-argument alloca wrapping trick:
I've just realized this doesn't work for variable-length
allocation:
T[] stack(T)(size_t N, void* m = alloca(T.sizeof * N))
Error: undefined identifier N, did you mean alias T?
N is not visible in the caller's scope.
It does, just alias it.
//----
import std.stdio;
import core.stdc.stdlib:alloca;
T* stack(T)(void* m = alloca(T.sizeof))
{
return cast(T*)m;
}
T[] stack(T, alias N)(void* m = alloca(T.sizeof * N))
{
return (cast(T*)m)[0 .. N];
}
void main(string[] args)
{
int* p = stack!int();
int[] arr = stack!(int, 5)();
*p = 2;
arr[0] = 5;
writeln(*p);
writeln(arr);
}
//----
