note afoken <p>Looking at the history of Perl 5, it is very unlikely that a perl compiled with default settings will break old code. One of the top priorities of Perl 5 is backwards compatibility at (nearly) all costs. This is easily to see with [mod://strict] and [mod://warnings], both are off by default simply because they could break old, dirty scripts. [doc://say], [doc://given]-[doc://when], need to be enabled explicitly, because old scripts may have used those words as function names and would break otherwise. Smart match and defined-or are disabled by default, Perl 5 still accepts Perl 4 function calls with a <c>&</c> in front of the function name, and so on.</p> <p>Another problem with a parallelizing <c>grep</c> is that it will likely need threads. Threads are still optional in Perl 5, many modules are still not thread-safe, and the perl interpreter would have to add a lot of behind-the-scenes tricks to make sure a parallelizing <c>grep</c> build-in behaves exactly identically to a non-parallelizing <c>grep</c> under all circumstances (including abuse as <c>map</c> or <c>for</c>), except for the better performance. I doubt that all that extra code required would make <c>grep</c> significantly faster.</p> <p>So, I think it is very unlikely that we will see a parallelizing <c>grep</c> in Perl 5, and it is even more unlikely that any improved <c>grep</c>, parallelized or not, will - by default - behave differently than <c>grep</c> in Perl 5.0.0, except for the performance or memory usage. For a dramatically improved, but incompatible <c>grep</c>, we can expect to see some pragma enabling it, perhaps <c>use feature qw(parallelgrep);</c> or <c>use parallelgrep;</c>.</p> <p>[id://997448], if you want to be really paranoid about <c>grep</c> and <c>map</c> behaviour, add a test for the expected behaviour to your installer. Something like this:</p> <c> #!/usr/bin/perl use strict; use warnings; use Test::More tests=>2; is(join(":",grep { $_%2==0 } 1..6),"2:4:6","grep keeps order"); is(join(":",map { 1+$_ } 1..6),"2:3:4:5:6:7","map keeps order"); </c> <p>Alexander</p> <div class="pmsig"><div class="pmsig-747201"> --<br> Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-) </div></div> 997453 997553