http://www.perlmonks.org?node_id=1019537


in reply to Re^2: Managing capture
in thread Managing capture

Competence is always nice sure, but I don't understand how destructors help. They aren't invoked unless an object is destroyed, which it won't be if it paricipates in a cycle.

I think you understand pefectly :)

If you're accepting callbacks and storing them in an object, you can made a practice of using PadWalker and checking for closures

A slightly simpler check could be made using Devel::Refcount but why bother when PadWalker can do it :)

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Re^4: Managing capture
by jbert (Priest) on Feb 19, 2013 at 12:55 UTC

    Yes, that would work. However, the drawbacks of this to me are:

    1. the check happens at runtime, not compiletime
    2. it requires each method taking a callback to implement the cycle check. that might be in 3rd party code and so require additional wrapping etc.

      ...

      Yup,

      otoh, its cheap check (cheaper than universal competence )

      and simpler to write than a pragma like autovivification -- have you looked at that thing? it walks the perl op-tree using c --- scary :)