Re: When do named subs bind to their variables? (Re: Questionable scope of state variables ([perl #113930] Lexical subs))

[Damian Conway]

Father Chrysostomos asked:

> What I am really trying to find out is when the subroutine is actually
> cloned,

Yes. It is supposed to be (or at least must *appear* to be),
and currently is (or appears to be) in Rakudo.


> and whether there can be multiple clones within a single call of
> the enclosing sub.

Yes. For example, a lexical sub might be declared in a loop inside the
enclosing sub, in which case it should produce multiple instances, one
per iteration.

For example, this:

    sub outer_sub () {
        for (1..3) {
            state $call_num = 1;
            my sub inner_sub {
                state $inner_state = (1..100).pick; # i.e. random number
                say "    [call {$call_num++}] \$inner_state = $inner_state";
            }

            say "\nsub id: ", &inner_sub.id;
            inner_sub();
            inner_sub();
        }
    }

    outer_sub();

produces:

    sub id: -4628941774842748435
        [call 1] $inner_state = 89
        [call 2] $inner_state = 89

    sub id: -4628941774848253711
        [call 3] $inner_state = 16
        [call 4] $inner_state = 16

    sub id: -4628941774839825925
        [call 5] $inner_state = 26
        [call 6] $inner_state = 26

under Rakudo


BTW, Both the above "yes" answers are consistent with (and can be
inferred from) the previous explanation that:

        my sub foo { whatever() }

 is just a syntactic convenience for:

        my &foo := sub { whatever() }

HTH,

Damian