On Thu, Sep 21, 2006 at 10:03:45PM -0700, Jonathan Lang wrote:
: How would I construct a capture literal that has both an invocant and
: at least one positional argument? How do I distinguish this from a
: capture literal that has no invocant and at least two positional
: arguments?
:
: Gut instinct: if the first parameter in a list is delimited from the
: rest using a colon instead of a comma, treat it as the invocant;
: otherwise, treat it as the first positional argument.
That is correct.
: This would mean that the rules for capturing are as follows:
:
: * Capturing something in scalar context: If it is a pair, it is
: captured as a named argument; otherwise, it is captured as the
: invocant.
:
: * Capturing something in list context: Pairs are captured as named
: arguments; the first non-pair is captured as the invocant if it is
: followed by a colon, but as a positional argument otherwise; all other
: non-pairs are captured as positional arguments.
Capture literals ignore their context like [...] does.
: So:
:
: $x = \$a; # $$x eqv $a
: $x = \:foo; # %$x eqv { foo => 1 }
: $x = \($a,); # @$x eqv ( $a ); is the comma neccessary, or are the
: () enough?
I think the () is probably enough.
: $x = \($a:); # $$x eqv $a
: $x = \(:foo); # %$x eqv { foo => 1 }; assuming that adverbs can go
: inside ().
: $x = \($a, $b) # @$x eqv ($a, $b)
: $x = \($a: $b) # $$x eqv $a; @$x eqv ($b)
: $x = \:foo ($a: $b, $c):bar<baz> <== $d, $e <== flag => 0; # results
: on next three lines:
: # $$x eqv $a
: # @$x eqv ($b, $c, $d, $e)
: # %$x eqv { foo => 1, bar => 'baz', flag => 0 }
Ignoring the syntax error, yes.
: Note that this approach makes it impossible for a pair to end up
: anywhere other than as a named argument in the capture object; while
: this makes sense when the capture object is being used as a proxy
: argument list, it makes less sense when it is being used as the
: equivalent of perl 5's references, and thus is probably a bug.
If you say "flag" => 0 it comes in as a pair rather than a named arg.
Larry
