I'm using Catalyst to build an application, and are using the Catalyst::Controller::BindLex module to keep the code more readeable:

    my $value :Stashed = 1;
[download]

in stead of

    $c->stash( value => 1 );
[download]

This is all great stuff until you have:

    sub action
         : Chained('other_action')
    {
        my $value: Stashed;
        #
        # a bit of code using $value
        #
        my $value: Stashed = 1;
    }
[download]

The last line was there in the initial iteration of the action, the first line got added after some redesign.

Catalyst server started up as usual with a summary of actions, paths, plugins, and a lot of my own debug prints. The first notice something was wrong was when I got:

    panic: Can't find SCALAR(0x3240d90) in the the caller's lexical pa
+d
[download]

This sent me on a merry chase through all the internals using the debugger. Somehow BindLex saw a different address for $value than the one I saw in the debugger. After a couple of hours, lots of coffee, and some silly experiments I decided to take a shower and go to bed. It was after 5AM after all....

Somewhere between shower and bed it dawned on me. The reason BindLex was seeing a different address must be because there were 2 vars with the same name in the subroutine's scope!! So I went back and looked closely at the output of the server start again, and there it was, as the first line of output:

    "my" variable $value masks earlier declaration in same scope.
[download]

So, lessons learned:

• There's such a thing as too much debugging output
• There is some really clever magic going on in BindLex, Devel::Caller and PadWalker. Kudo's for the people who came up with that code.
• There is a point where focussing too much on a problem becomes counter-productive. Stop and go do something else and enlightenment follows.

--
Lyon

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