If you are given just filenames on the command line, you can simply use <> and Perl will read them for you. That will also work if you get your input from STDIN, so it's the most flexible way of handling things - and it's less code for you to write too.

Here's one stab at cleaning this up:

#!/usr/bin/perl -w
use strict;

#%GROUP    ALSMS_consolidation
#%CHPTR    ALSMS_consolidation
#%SBCH1    WORK_switch_id

print "group ^ chapter ^ name ^ description\n";

my (%outer, $group, $chapter);

while(<>) {
    chomp;
    @line = split /\s+/;

    if(/^\%SBCH1/) {
        my ($key, $value);

        print "$key: ", join(", ", @$value), "\n\n"
            while ($key, $value) = each %outer

        %outer=();
    }
    elsif(/^\%GROUP/) {
        $group = $line[1];
    }
    elsif(/^\%CHPTR/) {
        $chapter = $line[1];
    }
    elsif(/^\%/) {
        push @{$outer{$line[0]}}, join ' ', @line[1 .. $#line];
    }
}

[download]
At this point I'd move all the cases into an hash and let the regex engine pick out the right one for me. The array formerly stored in @line is now passed through the parameter list. I put these all into an array first because the order of keys is important for the regex built from it. 
#!/usr/bin/perl -w
use strict;

#%GROUP    ALSMS_consolidation
#%CHPTR    ALSMS_consolidation
#%SBCH1    WORK_switch_id

my (%outer, $group, $chapter);

my @handler = (
    SBCH1 => sub {
        my ($key, $value);
        print "$key: ", join(", ", @$value), "\n\n"
            while ($key, $value) = each %outer
        %outer=();
    },
    GROUP => sub { $group = $_[1] },
    CHPTR => sub { $chapter = $_[1] },
    "" => sub { push @{$outer{$_[0]}}, join ' ', @_[1 .. $#line] },
);

my %handler = @handler;

my $rx = do {
    my @key;
    while(@handler) {
        # take two element from front, throw away the second 
        my ($key) = splice @handler, 0, 2;
        push @key, $key;
    }
    join '|', @key;
};
$rx = qr/^\%($rx)/;

print "group ^ chapter ^ name ^ description\n";
while(<>) {
    if(/$rx/) {
        chomp;
        $handler{$1}->(split /\s+/);
    }
}

[download]

Note that now, the loop doesn't chomp and split the string unless it actually found a handled tag at the front of the string - it's always good not to do any more work than necessary.

It does look more complicated now - and indeed, if you really, really won't ever need any more than you originally had, it may not even be worth it. But if you ever have to extend your code, it is quite helpful to work with hashes of subroutines rather than use huge if/elsif blocks.

Makeshifts last the longest.

In reply to Re^3: push to a hash of arrays by Aristotle
in thread push to a hash of arrays by aennen

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