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Re^3: What's the weaken here for?

by BrowserUk (Pope)
on Jan 20, 2012 at 03:16 UTC ( #948876=note: print w/replies, xml ) Need Help??

in reply to Re^2: What's the weaken here for?
in thread What's the weaken here for?

The author must have done this for some reason...

Because in the real code, unlike your simplification of it, the weakened sub reference forms a closure over itself:

$wrapper = sub { $self->unsubscribe($name => $wrapper); $cb->(@_); };

Ie. It contains a circular reference which would leak memory without the weakening.

For example, with the weaken commented, this leaks like a sieve:

#! perl -slw use strict; use Scalar::Util qw[ weaken ]; sub once { my $wrapper; $wrapper = sub { return $wrapper->(); }; # weaken $wrapper; return $wrapper; } once for 1 .. 1e9;

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
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In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

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