map() abuse or child with a chainsaw

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Re: map() abuse or child with a chainsaw by demerphq (Chancellor) on May 13, 2002 at 14:15 UTC
Im assuming that your "arrested" comment only applies to "some people". I use map all the time. And when its used right it makes code clearer not the opposite. The above is just a joke as it really says `shift @ARGV;` [download] My guess is that it should have said `# drop first two arguments map shift(@ARGV),(0,1);` [download] And your colleague got confused. Which really isnt anything to do with map. Yves / DeMerphq --- Writing a good benchmark isnt as easy as it might look.	[reply] [d/l] [select]
Re: Re: map() abuse or child with a chainsaw by kappa (Chaplain) on May 13, 2002 at 14:29 UTC
If I think of future readers of my code I'll write: `map shift(@ARGV), qw(two times);` [download] ...or (best of all)... `shift(@ARGV); shift(@ARGV);` [download] But this guy I wrote about, should only be allowed to use straight foreach loops from now on :=E (I'm a little emotive right now, excuse me). At least he won't be able to abuse arrayref constructor for plain old parens.	[reply] [d/l] [select]
(jeffa) 3Re: map() abuse or child with a chainsaw by jeffa (Bishop) on May 13, 2002 at 14:39 UTC
Just for sheer TIMTOWTDI: `@ARGV = @ARGV[2..$#ARGV]; # or for the paran paranoid: @ARGV = (@ARGV)[(2..$#ARGV)];` [download] ... but i don't like copying the ARGV array back to itself. More readable might be: `my $discard1 = shift; my $discard2 = shift;` [download] Out of curiosity, why would one even want to discard the first two arguments like that anyway? Seems like a bad idea in the first place. Hmmmm ... sounds like time to pull out one of the Getopt modules to me. ;) jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l] [select]
Re: 3Re: map() abuse or child with a chainsaw by Biker (Priest) on May 13, 2002 at 20:22 UTC
Re: 3Re: map() abuse or child with a chainsaw by kappa (Chaplain) on May 13, 2002 at 15:13 UTC
Re: Re: Re: map() abuse or child with a chainsaw by demerphq (Chancellor) on May 13, 2002 at 15:55 UTC
`map shift(@ARGV), qw(two times)` [download] Well, no dont do that. :-) A very good hint is that you are using map in void context. Thats dumb. (no offense to obfuscators at large ;-). Map is _meant_ to return a set of values, its not meant to be used as a for loop. (In fact my personal belief is that map() and grep() are sorely sorely misnamed. They should be called apply() and filter(), but thats another flame-war iykwim) I would say that your second choice is preferred, or possibly `shift @argv for (1,2);` [download] But map in void context? No thanks. Oh and of course, using Getopt would be a good idea too. (jeffa++) Yves / DeMerphq --- Writing a good benchmark isnt as easy as it might look.	[reply] [d/l] [select]
Re: map() abuse or child with a chainsaw by particle (Vicar) on May 13, 2002 at 14:44 UTC
if i were removing values from @ARGV, i'd make it very clear. splice makes the intent obvious, as does an assignment to undef. additionally, it avoids the bad practice of using map in void context. `# drop first two arguments of @ARGV (undef, undef) = splice @ARGV, 0, 2;` [download] oh, and if the coder mistakenly typed `[undef, undef] = ...`, it generates a compile-time error -- no need to rely on warnings and strict. ~Particle accelerates	[reply] [d/l] [select]
Re: map() abuse or child with a chainsaw by rinceWind (Monsignor) on May 13, 2002 at 14:33 UTC
Not sure that this shouldn't be called shift abuse rather than map abuse, or possibly anonymous arrayref confusion. Consider the equally egregious `shift(@ARGV) foreach ([0,1]);` [download] However, the two sorts of brackets does give it a more unnatural feel. This is an example of confusing anonymous arrayrefs with lists, which IMO belongs in the list of traps for the unwary. I have seen several examples of Perl newbie code which has made this mistake, and it is on my checklist of things to look out for when helping people spot bugs.	[reply] [d/l]
Re: map() abuse or child with a chainsaw by perrin (Chancellor) on May 13, 2002 at 17:08 UTC
I've also seen many abuses of map. If you see someone using things like map frequently, it's usually a sign that the person doesn't really have a good grasp on Perl and is trying to apply one solution to every prolem. This might be a clearer way to do it: `# ignore first two args my (undef, undef, $foo, $bar, $baz) = @_;` [download] A hash of named parameters would be even better.	[reply] [d/l]