in reply to Scope and Context

I hope you won't take this the wrong way, but that code is very hard to read. It's cool to do things like this with eval, but not a good idea from a maintenance perspective most of the time. I would have arranged it something like this (untested): 
my @matches = get_matches($file);

sub get_matches {
    my $file = shift;
    return unless (-e $file && -r _);

    local *FH;
    sysopen FH, $file, O_RDONLY;
    flock FH, 8;
    map { chomp; qr/$_/ } <FH>;
}

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I don't think the map is a big deal here, since you want the return value. I'm not sure it's worth messing around with sysopen though (I've never needed to use it, so I don't even know if it still works the way I rearranged it), and hard-coding the constant "8" is probably not a good idea either. I expect you know all this and were just posting to point out other things, but maybe someone else reading this didn't.

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Re: Re: Scope and Context
by rob_au (Abbot) on Nov 14, 2001 at 07:02 UTC
    I hope you won't take this the wrong way, but ...

    Nah, never taken the wrong way ... *memo to self - add perrin to the list* ... :)

    I understand your point with regard to readability ... I have been guilty of writing some horrendously difficult code to decipher before, purely without intent - The reason for the embedding of the subroutine within the code at this point is so that the regular expressions in the file are loaded entirely within the BEGIN {} block. Yes I can still call the subroutine from this point, but for my own mindset, I like keeping such initialisation code in the one place. Nevertheless, your point is well noted ...

    The hard-coding of the constant 8 is more of an oversight, but one which I should most definitely correct - Guess that's what happens when you get too pensive regarding programming methodology and ignore the practicalities *grin*

     

    Ooohhh, Rob no beer function well without!

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      The reason for the embedding of the subroutine within the code at this point is so that the regular expressions in the file are loaded entirely within the BEGIN {} block. Yes I can still call the subroutine from this point, but for my own mindset, I like keeping such initialisation code in the one place.

      You could put the sub definition in the BEGIN block...

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        If you're never going to call the sub from outside the BEGIN block then maybe something like: 
            BEGIN {
        my $get_regexes = sub {
             ...
           return map {...}
        };
        ...
    }

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        Which has the advantage of keeping the subroutine private.

        Oh yes, don't forget that in recent perl you can do open my $fh, ..., which is far nicer than 

            local *FH; 
    open FH, ...

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In Section Meditations