Fine tuning my condition statement

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Fine tuning my condition statement by Aristotle (Chancellor) on Nov 20, 2002 at 18:54 UTC
Regex alternation is costly and somewhat crufty. Building a hash works, but I'd prefer to at least do it non-iteratively: `my %stop; @stop{qw(first second third)} = (); next if exists $stop{$field};` [download] Personally, I'd use the following: `next if grep $field eq $_, qw(first second third);` grep in scalar context returns the number of matches. Makeshifts last the longest.	[reply] [d/l] [select]
Re: Fine tuning my condition statement by strider corinth (Friar) on Nov 20, 2002 at 18:28 UTC
One way would be this: `next if $field =~ /^(first\|second\|third)$/;` [download] The '^' matches the beginning of a string, and the '$' matches the end, emulating an 'eq' function for whatever's in between them. The '\|'s are roughly equivalent to an 'or' statement: this will match 'first' or 'second' or 'third'. Update: added explanation, and parens, thanks to Enlil. -- Love justice; desire mercy.	[reply] [d/l]
Re: Re: Fine tuning my condition statement by Anonymous Monk on Nov 20, 2002 at 20:25 UTC
Thanks for everyones help and answers.	[reply]
Re: Fine tuning my condition statement by fruiture (Curate) on Nov 20, 2002 at 18:29 UTC
There's no real reason to shorten this if it will stay that way. Shorter is not always better. You could make it more scalable like that: `next if exists { map {$_=>undef} qw(first second third) }->{ $field }` [download] But that is certainly less effivient than hard-coded! Use this (or something like it) only if you need this point to be that extendable. -- http://fruiture.de	[reply] [d/l]
Re: Fine tuning my condition statement by BrowserUk (Patriarch) on Nov 20, 2002 at 19:13 UTC
Or even (though some might consider it hookey :^) `next if 1+index( 'first Second third', $field );` [download] With the caveat that if $field can contain spaces, you need to use a different delimeter, and pick one that cannot be a part of $field. "\cA" is a favorite of mine. Okay you lot, get your wings on the left, halos on the right. It's one size fits all, and "No!", you can't have a different color. Pick up your cloud down the end and "Yes" if you get allocated a grey one they *are* a bit damp under foot, but someone has to get them. Get used to the wings fast cos its an 8 hour day...unless the Govenor calls for a cyclone or hurricane, in which case 16 hour shifts are mandatory. Just be grateful that you arrived just as the tornado season finished. Them buggers are real work.	[reply] [d/l]
Re: Fine tuning my condition statement by nothingmuch (Priest) on Nov 20, 2002 at 18:57 UTC
You could also do something like: `$field eq $_ and next for (qw/first Second third/);` [download] But I suspect It'll have a bit of an overhead... This saves the typing, but avoids a regex if you don't want to get into that. -nuffin zz zZ Z Z #!perl	[reply] [d/l]