[Issue 6557] Inplace enum literals
http://d.puremagic.com/issues/show_bug.cgi?id=6557 bearophile_h...@eml.cc changed: What|Removed |Added Status|NEW |RESOLVED Resolution||INVALID --- Comment #5 from bearophile_h...@eml.cc 2011-09-09 03:14:19 PDT --- The basic idea is cute, but I think it currently doesn't work. So I close this enhancement request, to be reopened if better ideas come. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 6557] Inplace enum literals
http://d.puremagic.com/issues/show_bug.cgi?id=6557
--- Comment #4 from Kenji Hara 2011-08-27 07:15:29 PDT ---
My thought case is following code.
void foo()(int n){} // 1
void foo()(enum {a, b} arg) {} // 2
void main() {
int a;
foo(a); // 1 or 2 ?
}
To determine the signature of foo, 'a' is judged as integer typed variable, and
1st foo overload is selected. 2nd version of foo is never selected.
And this is natural behavior guided from the current specification.
But this enhancement is require to determine foo's signature *before* argument
types. This is a serious conflict.
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[Issue 6557] Inplace enum literals
http://d.puremagic.com/issues/show_bug.cgi?id=6557
--- Comment #3 from bearophile_h...@eml.cc 2011-08-27 05:06:36 PDT ---
(In reply to comment #1)
> I think the enum scope inference from their member name is nearly impossible,
> because D has template function.
> The feature requires a function signature to determine the argument types, but
> template function call requires argument types to determine the function
> signature!
Do you mean this problem?
void foo(T)(T x, enum : T { A, B }) {}
void main() {
typeof(foo.A) a = foo.B;
foo(a);
}
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[Issue 6557] Inplace enum literals
http://d.puremagic.com/issues/show_bug.cgi?id=6557
--- Comment #2 from bearophile_h...@eml.cc 2011-08-26 16:31:38 PDT ---
(In reply to comment #1)
> In following case, what does foo receive as arg?
>
> void main()
> {
> typeof(foo.a) E;
> E a = foo.b;
> foo(a); // == foo(foo.a) or foo(foo.b) ?
> }
Thank you for finding this problem. I think that's a quite uncommon case, it's
a bug of the programmer. So this bad corner case is not enough to kill the
whole idea. In this case of actual ambiguity I think D has to act like in this
case:
struct Foo {
int x;
}
void main() {
int x;
Foo f;
with (f)
x++; // line 8, error
with (f) {} // no error here, no actual ambiguity
}
test.d(8): Error: with symbol test.Foo.x is shadowing local symbol test.main.x
void foo(enum {a, b} arg) {}
void main() {
auto a = foo.b;
foo(a); // Error: ambiguity...
}
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[Issue 6557] Inplace enum literals
http://d.puremagic.com/issues/show_bug.cgi?id=6557
--- Comment #1 from Kenji Hara 2011-08-26 05:14:00 PDT ---
> void foo(enum {a, b} arg) {
> if (arg == b) {}
> if (arg == foo.a) {} // alternative syntax
> }
I have one question.
In following case, what does foo receive as arg?
void main()
{
typeof(foo.a) E;
E a = foo.b;
foo(a); // == foo(foo.a) or foo(foo.b) ?
}
I think the enum scope inference from their member name is nearly impossible,
because D has template function.
The feature requires a function signature to determine the argument types, but
template function call requires argument types to determine the function
signature!
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