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Re: Control Flow - Multiple returns or nested conditionals

by TomDLux (Vicar)
on Oct 07, 2010 at 20:48 UTC ( #864084=note: print w/replies, xml ) Need Help??

in reply to Control Flow - Multiple returns or nested conditionals

I very much like early exits ( return, next,last ) when they avoid getting deep into stuff, especially dealing with exceptions, errors, irregularities. This example allows empty lines and comments in a data file.

open my $datafile ... LINE: while ( my $line = <$file> ) { next LINE unless length $line; next LINE if ( $line =~ m{\A \s* #}xms; process $line; }

If you're selecting one of several possible return values, I think it better to determine the value and return it in a single place. Otherwise you have a situation where a return value of XYZ may have arisen from this return statement or from that return statement. If the blocks are more than a few lines long, it may be worth encapsulating it into a named subroutine. That way the main block is short and easy to read:

if ( option_A( $line ) ) { $retval = do_this_complicated_thing( $line ); } elsif ( option_B( $line ) { retval = 'alphagetti'; retval .= ' and maple syrup' if $option_C( $line ); } else { $retval = 42; } return $retval;

As Occam said: Entia non sunt multiplicanda praeter necessitatem.

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