Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Chris Angelico <rosuav@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: breaking out of outer loops
Date: Tue, 8 Mar 2016 10:47:16 +1100
Lines: 54
Message-ID: <mailman.5.1457394438.15725.python-list@python.org>
References: <nbl1md$1lvd$1@gioia.aioe.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
In-Reply-To: <nbl1md$1lvd$1@gioia.aioe.org>
Precedence: list
Xref: csiph.com comp.lang.python:104275

On Tue, Mar 8, 2016 at 10:09 AM, Fillmore <fillmore_remove@hotmail.com> wrote:
> For the record, here's a Perl script of mine I'm trying to port...there may
> be 'malformed' lines in a TSV file I'm parsing that are better discarded
> than fixed.
>
> my $ctr = 0;
> OUTER:
> while($line = <FILE>) {
>
>     $ctr++;
>     if ($ctr < 5) {next;}
>
>     my @allVals  = split /\t/,$line;
>
>     my $newline;
>     foreach my $i (0..$#allVals) {
>
>         if ($i == 0) {
>             if ($allVals[0] =~ /[^[:print:]]/) {next OUTER;}
>
>             $newline =  $allVals[0];
>         }
>
>         if (defined $headers{$i}) {
>
>             #if column not a number, skip line
>             if ($allVals[$i+1] !~ /^\d+$/) {next OUTER;}
>
>             $newline .= "\t".$allVals[$i+1];
>         }
>     }
>     print $newline."\n";
>
> }

I'm not too fluent in Perl, but my understanding here is that "next
OUTER" is equivalent to Python's 'continue' statement, right? So your
flow control is roughly this:

for _ in range(5): skip header row
for line in file:
    for cell in split(line):
        if bad_cell_value:
            break # Skip out of the inner loop now
    else:
        print_stuff # We didn't break

Does that look right? The key here is that a 'for' loop has an 'else'
clause, which happens if there's no 'break' in the main loop. I think
that's what you're after, here; you get to break out of "the loop and
a little bit more", so to speak. The outer loop is actually immaterial
here.

ChrisA