Re^2: Parsing command line options without knowing what they are

[DrWhy]

Thanks, I may use some of the ideas in here for my own parser.

[BrowserUk]

YW. I later looked inside some of the existing getopts modules to see what other rules they implement, and boy are they ever complicated. Reverse engineering the rules from them would be a nightmare.

Here's a slightly cleaner refactoring of the above:

sub getOpts {
    my %opts;
    my @toDelete;
    for( my $i=0; $i < @ARGV; ++$i ) {
        $_ = $ARGV[ $i ];
        if( m[^-(.)(.*)$] ) {
            my( $first, $rest ) = ( $1, $2 );
            push @toDelete, $i;
            next unless defined $first;
            if( $first ne '-' ) {
                $opts{ $_ } = 1 for $first, split'',$rest;
                next;
            }
            last if $rest eq '';
            if( $ARGV[ $i+1 ] !~ m[^-] ) {
                $opts{ $rest } = $ARGV[ ++$i ];
                push @toDelete, $i;
            }
            if( $rest =~ m[^no(.+)$] ) {
                $opts{ $1 } = 0;
            }
            else {
                $opts{ $rest } = 1;
            }
        }
    }
    splice @ARGV, $_, 1 for reverse @toDelete;
    return %opts;
}

[DrWhy]

Nice. Especially nice since I've been doing alot of refactoring like this the last few weeks on code written by much less experienced Perl programmers. I'm curious about this line, though:

            next unless defined $first;

I don't think it's ever possible for $first to be undefined. If the regex in your if matches, the first capture will always have to be one character long, right? Never undefined?

[BrowserUk]

I don't think it's ever possible for $first to be undefined

You're right of course++

My only excuse is that it is an artifact of the iterative development process I went through as I tried to handle each different case. I think the test made sense at some point; but then again, maybe not :)

During the refactoring, I just attempted to remove some levels of nesting by moving things around, without breaking anything. I didn't actually consider why each condition was there at that point. It just highlights the value of peer review :)