On Tue, 31 May 2011 19:32:59 -0400, Nick Sabalausky <a@a.a> wrote:
"Nick Sabalausky" <a@a.a> wrote in message
news:is3tk5$1j2n$1...@digitalmars.com...
"Timon Gehr" <timon.g...@gmx.ch> wrote in message
news:is3rb5$1g32$1...@digitalmars.com...
It works for me. Are you sure you did not accidentally break some other
part of
your __traits(compiles,...) ?
My minimal test case:
template isIGizmo(T){enum isIGizmo=__traits(compiles,{static
assert(T._this_implements_interface_IGizmo);});}
mixin template declareInterface(string interfaceName){
mixin(`enum _this_implements_interface_`~interfaceName~`=true;`);
mixin(`static assert(
is`~interfaceName~`!(typeof(this)),
"This type fails to implement `~interfaceName~`"
);`
);
}
struct Gizmo{mixin declareInterface!"IGizmo";}
static assert(isIGizmo!Gizmo);
void main(){}
Hmm, something screwey seems to be going on. Your test example works for
me too, but I could swear I've checked and double-checked everything
(including the "__traits(compiles,...)") , and made your test case and
my
example as close to each other as I can, and I still can't seem to
narrow
down what's different.
I do know this: In my code, I can't use typeof(this) because the
compiler
complains that "this" is only valid inside a member function. I have no
idea why doing that seems to work, even for me, in your test case.
I think typeof(this) just seems to be screwy. Check this out:
struct Gizmo {
static assert( is(typeof(this)==Gizmo) );
}
void main() {}
Error: static assert (is(typeof(__error) == Gizmo)) is false
But this is fine:
struct Gizmo {
alias typeof(this) Foo;
typeof(this)* ptr;
}
I think there are certain special situations where you can use
typeof(this). For example, as the return type for a static method.
*looks for doc* Couldn't find any documentation on it...
It's somewhat like static this, which is inflexible in how you write it.
-Steve
