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Re: Closure on Closures (beta)

by adrianh (Chancellor)
on Jun 25, 2003 at 16:36 UTC ( #268910=note: print w/replies, xml ) Need Help??

in reply to Closure on Closures

++ Nice summary.

Minor niggle. If it were me I would put a little bit more emphasis on lexical scoping and a little less emphasis on reference counting. When the value of a lexical variable is garbage collected is independent of whether a Perl closure is created. It's about scope - not memory usage. For example:

our $Global; sub make_closure { my %lexical; $Global = \%lexical; return sub { my $key = shift; @_ ? $lexical{$key} = shift : $lexical{$key}; }; }; { # here we make a closure my $c = make_closure(); # which we can use to set and get keys $c->(foo => 42); print "foo is ", $c->('foo'), "\n"; # at the end of the scope the closure goes away }; # but the referant is still around print "Global foo is ", $Global->{foo}, "\n";

Update: It might also be worth comparing what Perl does to languages without lexical capture like C.

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Re^2: Closure on Closures (beta)
by Anonymous Monk on Feb 28, 2005 at 11:56 UTC
    the examples in this section are some what complicated for a new learner of perl.specially calling subroutines

    Title edit by tye, restore prefix

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