Question

I was wondering if it’s possible to declare a global variable within a subroutine in Perl so that I can use that variable in a hooked void function, but limiting the damaging effects of the global by having it declared in a subroutine.

So the subroutine uses XML::Parser to collect the IDs of a bunch of elements, in a manner similar to:

sub getRecipeIDs {
    my $recipe = shift;
    my @elements = ();

    my $parser = new XML::Parser(Style => 'Tree',
        Handlers => {
            Start => sub {
                my ($expat, $element, %attrs) = @_;
                if ($element eq 'recipe') {
                    push @elements, $attrs{id};
                }
        }});

    $parser->parse($recipe);

    return @elements;
}

I’m also using strict in my script.

So I want to declare @elements in such a way that it is local to getRecipeIDs but is visible to the anonymous subroutine.

Thanks for your time, any help is greatly appreciated.

Answer 1

It should already work the way in which you’ve written your example. What you’re doing with “my $func = sub { ... }” is you create a closure which has access to the enclosing scope’s variables — in this case @elements.