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author | Abigail <abigail@abigail.be> | 2003-09-09 12:31:58 +0200 |
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committer | Rafael Garcia-Suarez <rgarciasuarez@gmail.com> | 2003-09-10 19:36:30 +0000 |
commit | 788611b6a6a160290f10302fc348e5dff91edc6e (patch) | |
tree | 5f33e98471e91b46634547597546c96c06a669ef /pod/perlfaq6.pod | |
parent | 084b8eeb79bb97cd6a1b051bc9b7db2007cf036f (diff) | |
download | perl-788611b6a6a160290f10302fc348e5dff91edc6e.tar.gz |
Remove the warning in perlfaq about using map in void context :
Subject: [PATCH perlfaq6] map in a void context.
Message-ID: <20030909083158.GA24125@abigail.nl>
p4raw-id: //depot/perl@21166
Diffstat (limited to 'pod/perlfaq6.pod')
-rw-r--r-- | pod/perlfaq6.pod | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/pod/perlfaq6.pod b/pod/perlfaq6.pod index 0a134c3740..168233bd1b 100644 --- a/pod/perlfaq6.pod +++ b/pod/perlfaq6.pod @@ -679,15 +679,18 @@ guaranteed is slowness.) See the book "Mastering Regular Expressions" hope to know on these matters (a full citation appears in L<perlfaq2>). -=head2 What's wrong with using grep or map in a void context? +=head2 What's wrong with using grep in a void context? -The problem is that both grep and map build a return list, -regardless of the context. This means you're making Perl go -to the trouble of building a list that you then just throw away. -If the list is large, you waste both time and space. If your -intent is to iterate over the list then use a for loop for this +The problem is that grep builds a return list, regardless of the context. +This means you're making Perl go to the trouble of building a list that +you then just throw away. If the list is large, you waste both time and space. +If your intent is to iterate over the list, then use a for loop for this purpose. +In perls older than 5.8.1, map suffers from this problem as well. +But since 5.8.1, this has been fixed, and map is context aware - in void +context, no lists are constructed. + =head2 How can I match strings with multibyte characters? Starting from Perl 5.6 Perl has had some level of multibyte character |