typeof and block statements

[Mafi]

Am 12.08.2010 15:13, schrieb simendsjo:
> The spec doesn't mention anything about block statements in typeof
> declarations.
>
> //typeof({1}) a; // found } expecting ;
> //typeof({1}()) b; // same as a
> typeof(1) c; // int
>
> I'm asking because isInputRange from std.range the idom from the b test:
>
> template isInputRange(R)
> {
> enum bool isInputRange = is(typeof(
> {
> R r; // can define a range object
> if (r.empty) {} // can test for empty
> r.popFront; // can invoke next
> auto h = r.front; // can get the front of the range
> }()));
> }
>
>
> Also... The unittest contains
> static assert(isInputRange!(int[]));
> static assert(isInputRange!(char[]));
>
> But arrays doesn't include these methods.. I don't understand a thing :(
The braces create an delegate which should be directly called after its 
  creation (this do the parens). If you put this into typeof, this 
delegate will never be created, we just get the type of calling it. The 
type of calling a delegate is of course the delegate's return type which 
is automatically deduced.
Your exampley a and b are invalid beacuse '1' is not a valid statement 
it's only a expression. 'return 1;' would work as expected.
Why does the spec don't mention it? It's beacuse a delegate is always a 
valid expresion. typeof has no special case of braces.

Mafi