Learning perl, after years...

It's really awesome that perl still has a lot to teach after years of programming experience :)

Encountered a code, which i can't interpret (so as my parser). This is a part of PPI::Lexer. We've got an array:

    @CURLY_LOOKAHEAD_CLASSES = (
        {},    # not used
        {
            ';'    => 'PPI::Structure::Block', # per perlref
            '}'    => 'PPI::Structure::Constructor',
        },
        {
            '=>'   => 'PPI::Structure::Constructor',
        },
    );
[download]

And somewhere else we have such code:

 elsif ( my $class = $CURLY_LOOKAHEAD_CLASSES[$position]
            {$Next->content} )
[download]

How does it work? We are assigning list element to the class and what is $Next block?

Thanks in advance

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Re: Learning perl, after years... (deref) by tye (Sage) on May 03, 2015 at 18:44 UTC
You seem to be paying way too much attention to the line break. `$position` is either 1 or 2. `$Next->content()` is expected to return `';'` or `'}'` when `$position` is 1 and to return `'=>'` when `$position` is 2. The code is a rather simple array look-up followed by a hash look-up: `my $class = $CURLY_LOOKAHEAD_CLASSES[$position]->{ $Next->content() };` [download] - tye	[reply] [d/l] [select]
Re^2: Learning perl, after years... (deref) by hurricup (Pilgrim) on May 03, 2015 at 19:55 UTC
Crap, till now didn't know that `$hashref->{key1}->{key2}->{key3}` can be written as `$hashref->{key1}{key2}{key3}` Thank you very much :)	[reply] [d/l] [select]