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Re: Flag variables

by gmax (Abbot)
on Mar 03, 2003 at 12:20 UTC ( #240003=note: print w/replies, xml ) Need Help??

in reply to Flag variables

As a significant example of why flags can be messy, check this particularly thorny source code.

I needed to use that module and I found out that it was faulty. I tried to fix it, but its logic eluded me. I contacted the author, who didn't do anything, and therefore I wrote my own parser using a rather different approach.

This module is supposed to parse chess games. The problem in this code is that it skips the last game in each file it parses. I was able to spot where the problem is. As for fixing it using the same labyrinth of flags system, I simply couldn't.

## ## WARNING! broken code ahead! ## my $FLAG=1; my $GAME=0; ## ## ... snip ## sub ReadGame { my $self=shift; my $continue=1; $self->_init(); do { if ( $continue == 2 ) { $continue = 0 } if ( $LINE =~/\[(.*)\]/ ) { my $line=$1; my ($key,$val,$junk)=split(/"/,$line); $key=~s/ $//g, $self->{$key}=$val; $GAME=0; } elsif ( $LINE !~/^$/) { $self->{Game}.=$LINE; $GAME=1; } elsif ( $GAME == 1 ) { $FLAG=0; } $LINE=<FICPGN>; if ( eof(FICPGN) && $continue == 1 ) { $continue = 2 } $LINE=~s/\r//; } while ( $FLAG==1 ); return ( $continue ) ; }
This code uses not one but THREE flags, transforming a would-be OOP module into a peculiar example of spaghetti code.
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