Aliasing and return, how does return work?

bsb has asked for the wisdom of the Perl Monks concerning the following question:

On Preserve @_ aliasing a (scalar||array) I wrap a scalar parameter into an array while preserving it's aliasing. A problem I've just encountered it that it doesn't preserve the aliasing on the $list container itself, and I think it's because "return $x" returns a copy of whatever and I can't think of an aliasing equivalent...

If that made no sense it doesn't really matter. I want a sub "ret" which will print "ALIAS" below

  DB<28> sub ret { return $_[0] }

  DB<29> $a = []; print \$_,"\n",\$a and \$_==\$a and print "ALIAS" fo
+r ret($a);
SCALAR(0x8201604)
SCALAR(0x8201b08)
[download]

What I want can probably be achieved in two steps:

&wrap_arg_one; for my $list ($_[0]) { ...}
[download]

but I'd prefer something like &shift_list in the post above

Brad

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Re: Aliasing and return, how does return work? by japhy (Canon) on Jun 30, 2004 at 03:31 UTC
Make it an lvalue function: `sub ret :lvalue { $_[0] }` [download] Notice: I didn't put return() in there -- that's a necessity for an lvalue function. _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area) `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply] [d/l]
Re^2: Aliasing and return, how does return work? by bsb (Priest) on Jun 30, 2004 at 04:37 UTC
I think this could work but I'm not having much joy so far. I'm still on perl version 5.6.1 which could easily be a factor. Will an lvalue sub work when called as &ret = 123? I ask because I'm trying to do parameter preprocessing for the caller and was doing it with &ret.	[reply]
Re^3: Aliasing and return, how does return work? by japhy (Canon) on Jun 30, 2004 at 05:01 UTC
I'm not sure if lvaluable subs work in 5.6.1. This code works for me with Perl 5.8.4: `sub ret :lvalue { $_[0] } sub foo { &ret++; print "ARGS: <@_>\n"; } my ($x, $y) = (10, 20); foo($x, $y); __END__ ARGS: <11 20>` [download] Make sure you aren't accidentally shifting the argument you're planning on setting before you set it. _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area) `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply] [d/l]
Re^4: Aliasing and return, how does return work? by bsb (Priest) on Jun 30, 2004 at 06:38 UTC


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