in reply to Re^2: recursive anonymous subroutines
in thread recursive anonymous subroutines

It's a recursive, i.e. leaking, reference.

Hmm... probably safer to keep the reference on the call stack, thus releasing it on exit.

For example, adopting the convention that the reference is always passed as the first parameter: 

my @factorials = map {

    $_[0] ||= sub {
        my $factor = pop;

        return $factor > 1
            ? &{$_[0]}($_[0],$factor-1) * $factor
            : 1;
    };

    &{$_[0]}($_[0],$_)} (3,5,7,9);

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..or.. 
sub make_call {
    goto $_[0];
}

my @factorials = map {

    make_call (sub {
        my $factor = $_[1];
    
        return $factor > 1
            ? make_call($_[0], $factor-1) * $factor
            : 1;
    }, $_);

} (3,5,7,9);

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Re^4: recursive anonymous subroutines
by Daryn (Sexton) on Apr 10, 2006 at 12:05 UTC
    Very nice! I believe your make_call version will shortly become a new idiom in my code. Many thanks!
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Re^4: recursive anonymous subroutines
by runrig (Abbot) on Apr 11, 2006 at 23:26 UTC
    Just thought I'd point out that this is an interesting reinvention of a previous post (though with one less level into the call stack due to the goto). Compare:
    # Your's:
sub make_call { goto $_[0] }

# Anonymonk's(slightly rearranged):
sub Y { $_[0]->(@_) }

    [download]
    Update: Well, it's more the same if you change your call to:
    make_call (sub {
        my $factor = $_[1];
   
        return $factor > 1
            ? $_[0]->($_[0], $factor-1) * $factor
            : 1;
    }, $_);

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