Re^4: map vs for\foreach.


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Re^4: map vs for\foreach.

by ikegami (Patriarch)

on Mar 13, 2015 at 17:39 UTC ( [id://1119980]=note: print w/replies, xml )

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in reply to Re^3: map vs for\foreach.
in thread map vs for\foreach.

Superstition makes me post-increment; I think it’s not slower anymore but was back in the dinosaur age.

Post-increment is necessarily slower since it requires making a copy of the scalar that pre-increment doesn't. However, Perl replaces post-increment operators in void context with pre-increment operators.

$ perl -MO=Deparse -e'$_++ for @a;'
++$_ foreach (@a);
-e syntax OK

$ perl -MO=Deparse -e'map { $_++ } @a;'
map {$_++;} @a;
-e syntax OK
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Re^5: map vs for\foreach. by karlgoethebier (Abbot) on Mar 13, 2015 at 18:31 UTC
BTW: `#!/usr/bin/env perl use strict; use warnings; use Data::Dump; my @original_data_set = ( 1 .. 10 ); dd \@original_data_set; my @modified_data_set = map { $_++} @original_data_set; dd \@original_data_set, \@modified_data_set; __END__ karl-mac-mini:monks karl$ ./1119980.pl [1 .. 10] ([2 .. 11], [1 .. 10])` [download] Best regards, karl «The Crux of the Biscuit is the Apostrophe»	[reply] [d/l]
Re^6: map vs for\foreach. by LanX (Saint) on Mar 13, 2015 at 18:38 UTC
So the so called "modified" set isn't really modified because its a post increment. While being consistent and logic it's indeed surprising, and a good reason to generally prefer pre-increments. edit Thanks seems like I have to rethink my habit. Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)} PS: Je suis Charlie!	[reply]