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Re: [perl #58236] [TODO][PDD19] make decision on open issue on .return d

To: Klaas-Jan Stol <parrotcode@gmail.com>
Subject: Re: [perl #58236] [TODO][PDD19] make decision on open issue on .return directive in pdd19
From: Allison Randal <allison@perl.org>
Date: Sat, 30 Aug 2008 11:40:16 +0200
Cc: perl6-internals@perl.org
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References: <RT-Ticket-58236@perl.org> <7b0e52b40808220315t1d360f05ob14a2c9184907063@mail.gmail.com> <rt-3.6.HEAD-29762-1219400211-1603.58236-72-0@perl.org> <48B90D02.80605@perl.org> <7b0e52b40808300216nc26ce7av1525d5887e5be60@mail.gmail.com>
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Klaas-Jan Stol wrote:
On Sat, Aug 30, 2008 at 11:04 AM, Allison Randal <allison@perl.org> wrote:

Yes, it will be deprecated, or at least renamed. The C<.return> directive
without parentheses is an old convention for passing a single return result,
and must always be sandwiched between  C<.begin_return> and C<.end_return>.

Do you mean this one? (see next)

.begin_return
.return "hi"
.return 42
.return 3.14
.end_return

(which is the same as:   .return ("hi", 42, 3.14)       )
Is the purpose of renaming this to make a clear distinction between the
'.return' directive in this long style of returning and the short one
('.return ()' )   ?

Yes. That whole set of directives would benefit from clearer naming. Perhaps:

  .set_return "hi" # return value passed, between .begin_return
                   # and .end_return
  .set_arg "foo"   # argument passed, between .begin_call and .end_call
  .get_result      # result retrieved, between .call and .end_call

And, there's another C<.return> without parentheses that performs a
tail-call, invoking a sub or method reusing the same return continuation.
 This should also be renamed.

Is the purpose to be more explicit on being a tailcall? (in that case, it
could be renamed as ".tailcall" or whatever -- but that's obvious)

Obvious is good.

The only directive that should be named C<.return> is the one that returns
a value or values (i.e. it's syntactic sugar for a whole collection of
low-level directives/opcodes).

and this would be:     .return ("hi", 42, 3.14)
right?

Yes.

Allison


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