(This is an extended repost of a message that I have put in D.learn.)

Sometimes I have code like this:

struct VeryLongNamedStruct {}
void foo(in VeryLongNamedStruct x = VeryLongNamedStruct(1)) {}
void main() {}

Or even:

void bar(in TupleFoo x = TupleFoo(TupleBar(2), TupleSpam(3))) {}

In those cases something I'd like to use "auto" in the function signature for the arguments that have a default value:

void foo(in auto x = VeryLongNamedStruct(1)) {}

Do you like? Is it safe enough? Is it useful enough? Is it too much work to implement?

A bit more complex case:

void spam(T)(const x = Foo!T(4)) {}

Bye,
bearophile

On Thursday, 27 June 2013 at 17:42:14 UTC, bearophile wrote:
> (This is an extended repost of a message that I have put in D.learn.)
>
> Sometimes I have code like this:
>
> struct VeryLongNamedStruct {}
> void foo(in VeryLongNamedStruct x = VeryLongNamedStruct(1)) {}
> void main() {}
>
> Or even:
>
> void bar(in TupleFoo x = TupleFoo(TupleBar(2), TupleSpam(3))) {}
>
> In those cases something I'd like to use "auto" in the function signature for the arguments that have a default value:
>
> void foo(in auto x = VeryLongNamedStruct(1)) {}
>
> Do you like? Is it safe enough? Is it useful enough? Is it too much work to implement?
>
> A bit more complex case:
>
> void spam(T)(const x = Foo!T(4)) {}
>
> Bye,
> bearophile

Alias supposed to be used for such cases, but auto can be used in paramenters too.

On Thu, 27 Jun 2013 19:58:58 +0200
"Maxim Fomin" <maxim@maxim-fomin.ru> wrote:

> On Thursday, 27 June 2013 at 17:42:14 UTC, bearophile wrote:
> > (This is an extended repost of a message that I have put in D.learn.)
> >
> > Sometimes I have code like this:
> >
> > struct VeryLongNamedStruct {}
> > void foo(in VeryLongNamedStruct x = VeryLongNamedStruct(1)) {}
> > void main() {}
> >
> > Or even:
> >
> > void bar(in TupleFoo x = TupleFoo(TupleBar(2), TupleSpam(3))) {}
> >
> > In those cases something I'd like to use "auto" in the function signature for the arguments that have a default value:
> >
> > void foo(in auto x = VeryLongNamedStruct(1)) {}
> >
> > Do you like? Is it safe enough? Is it useful enough? Is it too much work to implement?

I've noticed a need for that, too.


> but auto can be used in paramenters too.

It can? Cool!

On Thursday, 27 June 2013 at 20:24:46 UTC, Nick Sabalausky wrote:
> 
>> but auto can be used in paramenters too.
>
> It can? Cool!

Actually I meant "dmd does not support the feature now, but I see no reason for not supporting it".

In the meantime I have opened an enhancement request:
http://d.puremagic.com/issues/show_bug.cgi?id=10491

Henning Pohl has written a patch:
https://github.com/D-Programming-Language/dmd/pull/2270

And Kenji has written some comments in Bugzilla, explaining why he doesn't like this ER.

I usually trust Kenji judgement. So let's close down this idea?

Bye,
bearophile