• Adam D. Ruppe (7/7) May 21 2017 Why is that prohibited? I just wrote
• Adam D. Ruppe (7/8) May 21 2017 Well, not exactly work, it didn't actually instantiate the inner
• Vladimir Panteleev (4/5) May 21 2017 I think it's the same as foo!x!y. As for the reason - I think
• Stanislav Blinov (11/16) May 21 2017 I did encounter that a few times too, and my humble opinion is
• Daniel N (3/21) May 21 2017 I ran into this aswell.

Adam D. Ruppe <destructionator gmail.com> writes:

Why is that prohibited? I just wrote

template foo(x) { template foo(y) {}}

and did

foo!(x)!y

and it triggered that error. If I comment that line and use the 
hacked dmd, it seems to work.


So why is that error there?

Adam D. Ruppe <destructionator gmail.com> writes:

On Sunday, 21 May 2017 at 13:08:18 UTC, Adam D. Ruppe wrote:
 If I comment that line and use the hacked dmd, it seems to work.

Well, not exactly work, it didn't actually instantiate the inner 
template like it probably should have.

So is it just not implemented correctly and became an error 
because y'all never got around to fixing the bugs, or is it 
prohibited by design? If so, why? Is it impossible to implement 
correctly?

Vladimir Panteleev <thecybershadow.lists gmail.com> writes:

On Sunday, 21 May 2017 at 13:08:18 UTC, Adam D. Ruppe wrote:
 foo!(x)!y

I think it's the same as foo!x!y. As for the reason - I think 
because the order is possibly ambiguous or something? You could 
interpret it as either (foo!x)!y or foo!(x!y).

Stanislav Blinov <stanislav.blinov gmail.com> writes:

On Sunday, 21 May 2017 at 13:42:50 UTC, Vladimir Panteleev wrote:
 On Sunday, 21 May 2017 at 13:08:18 UTC, Adam D. Ruppe wrote:
 foo!(x)!y

 I think it's the same as foo!x!y. As for the reason - I think 
 because the order is possibly ambiguous or something? You could 
 interpret it as either (foo!x)!y or foo!(x!y).

I did encounter that a few times too, and my humble opinion is 
that there should not be any ambiguity, it should just be 
left-to-right, i.e.:

foo!x!y is the same as (foo!x)!y, and

foo!x!y!z!w would be (((foo!x)!y)!z)!w

This is no different from

foo!x.bar, which is (foo!x).bar and not foo!(x.bar)

Allowing this will only help reduce boilerplate. If we do need 
different order, we could always explicitly instantiate 
beforehand.

Daniel N <no public.email> writes:

On Sunday, 21 May 2017 at 14:11:00 UTC, Stanislav Blinov wrote:
 On Sunday, 21 May 2017 at 13:42:50 UTC, Vladimir Panteleev 
 wrote:
 On Sunday, 21 May 2017 at 13:08:18 UTC, Adam D. Ruppe wrote:
 foo!(x)!y

 I think it's the same as foo!x!y. As for the reason - I think 
 because the order is possibly ambiguous or something? You 
 could interpret it as either (foo!x)!y or foo!(x!y).

 I did encounter that a few times too, and my humble opinion is 
 that there should not be any ambiguity, it should just be 
 left-to-right, i.e.:

 foo!x!y is the same as (foo!x)!y, and

 foo!x!y!z!w would be (((foo!x)!y)!z)!w

 This is no different from

 foo!x.bar, which is (foo!x).bar and not foo!(x.bar)

 Allowing this will only help reduce boilerplate. If we do need 
 different order, we could always explicitly instantiate 
 beforehand.

I ran into this aswell.
Agreed, just an arbitrary restriction.