in reply to Re^5: Accessing lexicals in other scopes dynamically by name
in thread Accessing lexicals in other scopes dynamically by name

Hmm.

I have never really looked at the Perl-internals, but I can vagly remember having seen an implementation of Scheme in Scheme.

If I remember correctly there was a data-structure containing all the variable-bindings for any lexical scope and every closure would simply keep a reference to this.

So in this approach there is not a "capturing of all lexicals" but simply remembering one data-structure regardless of how many variables were defined it.

Perl evidently does this differently and I even think that the inaccessabilty of certain lexial variables of which Perl could not see that the are going to be used in a closure is a weakness.

I will try this in Rakudo.

  • Comment on Re^6: Accessing lexicals in other scopes dynamically by name

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Re^7: Accessing lexicals in other scopes dynamically by name
by ikegami (Patriarch) on Jul 30, 2010 at 22:20 UTC

    So in this approach there is not a "capturing of all lexicals" but simply remembering one data-structure regardless of how many variables were defined it.

    You forgot the bit about placing them in the data structure to being with.

[reply]
      You forgot the bit about placing them in the data structure to being with.
      I made it not clear I think.

      This structure is initialized when a new lexial scope is encountered (pointing back to the enclosing environment) and new variable bindings are added whenever a new lexial variable is defined.

      It exists whether or nor a closure is created.

      All closures within this context then simply remember a reference to this structure and use it to look up variables.

      But Perl evidently does it differently it does not really matter..

[reply]

        It exists whether or nor a closure is created.

        You're talking about making references to variables all over the place to replace a few when an anon sub is created. That's a very big negative.

[reply]

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