Ingo Blechschmidt wrote:
>Hi,
>
>while fixing bugs for the imminent Pugs 6.2.10 release, we ran into
>several issues with magical pairs (pairs which unexpectedly participate
>in named binding) again. Based on Luke's "Demagicalizing pairs" thread
>[1], #perl6 refined the exact semantics [2].
>
>The proposed changes are:
>
>* "(key => $value)" (with the parens) is always a positionally passed
> Pair object. "key => $value" (without the parens) is a named
> parameter:
>
> sub foo ($a) {...}
>
> foo(a => 42); # named parameter "a", $a will be 42
> foo(:a(42)); # same
>
>
>
> foo((a => 42)); # positional parameter (a pair),
> # $a will be the Pair (a => 42)
> foo((:a(42))); # same
>
>
>
What about whitespace?
foo (a => 42); # Note space
Is that the first case (subcall with named arg) or the second case (sub
with positional pair)?
>* Passing a variable containing a Pair is always passed positionally:
>
> my $pair = (a => 42); # or :a(42)
>
> foo($pair); # positional parameter, $a will be the Pair (a => 42)
>
>* Unary "*" makes a normal pair variable participate in named binding:
>
> foo(*$pair); # named parameter "a", $a will be 42
>
>* Same for hashes:
>
> my %hash = (a => 1, b => 2, c => 3);
>
> foo(%hash); # positional parameter, $a will be \%hash
>
> foo(*%hash); # three named parameters
>
>Opinions?
>
>
>--Ingo
>
>[1] http://article.gmane.org/gmane.comp.lang.perl.perl6.language/4778/
>[2]
>http://colabti.de/irclogger/irclogger_log/perl6?date=2005-10-09,Sun&sel=528#l830
>
>
>
What's the most complete way to get the sub's arguments?
That is, for a sub that takes positional, optional, named, and variadic
(*) arguments, what's the best mechanism for grabbing the entire call?
Your reply to Uri:
> Uri Guttman wrote:
>> but what about lists and arrays?
>>
>> my @z = ( 'a', 1 ) ;
>> foo( @z ) # $a = [ 'a', 1 ] ??
>
>
> Yep.
Suggests that I cannot pass along parameters in the usual way:
sub foo(...)
{
bar(@_);
}
Does that work if I code it as
bar @_;
(which is huffmanly, but hardly intuitive).
=Austin
