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Well, you must be careful when you use match variables, especially when you work with big strings. But they aren't slow per se:

Update: Thank you all for your comments and suggestions (here and in the CB)! See How do I get what is to the left of my match? for an updated benchmark and better explanations.

use Benchmark qw(:all); use Regexp::MatchContext; my $count = 300000; my $seq = 'GGGTTGAAGTTTAGACCGCTCACAGTAGTTCTACCTATAGAAAAGATCATGAAAGAGGCGATC +AGAATGGTACTCGAATCCATTTACGATCCCGAGTTTCCAGACACATCGCATTTCCGCTCGGGTCAAGGC +TGCCACTCGGTCCTAAGACGGATCAAAGAAGAGTGGGGAATCTCTCGCTGGTTTTTAGAATTCGACATC +AGGAAGTGTTTTCACACCATCGACCGACATCGACTCATCCAAATTTTGAAGGAAGAGATCGACGATCCC +AAGTTCTTTTACTCCATTCAGAAAGTATTTTCCGCCGGACGACTCGTAGGAGTTGAGAGGGGCCCTTAC +TCCGTCCCACACAGTGTACTACTATCGGCCCTACCAGGCAACATCTACCTACACAAGCTCGATCAGGAG +ATAGGGAGGATCCGACAGAAGTACGAAATTCCGATTGTTCAGAGAGTCAGATCGGTTCTATTAAGGACA +GGTCGTCGTATTGATGACCAAGAAAACCCTGGAGAAGAAGCAAGCTTCAACGCTCCCCAAGACAACAGA +GCCATCATTGTGGGGAGCGTTAAGAGCATGCAACGCAAAGCGGCCTTTCATTCCCTTGTTTCGTCGTGG +CACACCCCCCCCACAAGCACCCTCCGGCTCAGGGGGGACCAGAAAAGGCCTTTCGTTTTCCCCCCTTCG +TCGGCCCTTGCCGTCTTCCTTAACAAGCCCTCGAGCCTTCTTTGCGCCGCCTTCCTCATAGAAGCCGCC +GGGTTGACCCCGAAGGCTGAATTCTATGGTGGAGAACGCTGTAATAATAATTGGGCCATGAGAGACCTT +CTTAAGTATTGCAAAAGAAAGGGCCTGCTGATAGAGCTGGGCGGGGAGGCGATACTAGTTATCAGGTCA +GAGAGAGGCCTGGCCCGTAAGCAGGCCCCCTTAAAAACCCATTACTTAATAAGGATTTGTTACGCGCGA +TATGCCGACGACTTACTACTGGGAATCGTGGGTGCCGTAGAGCTTCTCATAGAAATACAAAAACGTATC +GCCCATTTCCTACAATCTGGCCTGAACCTTTGGGTAGGCTCCGCAGGATCAACAACAATAGCTGCACGG +AGTACGGTAGAATTCCTTGGTACGGTCATTCGGGAAGTCCCTCCGAGGACGACTCCCATACAATTTTTG +CGAGAGCTGGAAAAGCGTCTACGGGTAAAGCACCGTATCCATATAACTGCTTGCCACCTACGCTCCGCC +ATCCATTCAAAGTTTAGGAACCTAGGTGATAGTATCCCGATCAAACAGCTGACGAAGGGGATGAGCAAA +ACAGGGAGTCTACAGGACGGGGTTCAACTAGCGGAGACTCTTGGAACAGCTGGAGTCAGAAGTCCCCAA +GTTAGCGTATTATGGGGGACCGTCAAGCACATCCGGCAAGGATCAAGGGGGATCTCGTTCTTGCATAGC +TCAGGTCGGAGCAACGCGTCATCGGACGTTCAACAGGTAGTCTCACGATCGGGCACTCATGCCCGTAAG +TTGTCATTGTATACTCCCCCGGGTCGGAAGGCGGCGGGGGAGGGAGGAGGACACTGGGCGGGATCTATC +AGCAGCGAATTCCCCATAAAGATAGAGGCACCTATAAAAAAGATACTCCGAAGGCTTCGGGATCGAGGT +ATCATTAGCCGAAGAAGACCCTGGCCAATCCACGTGGCCTGTTTGACGAACGTCAGCGACGAAGACATC +GTAAATTGGTCCGCGGGCATCGCGATAAGTCCTCTGTCCTACTACAGGTGCCGCGACAACCTTTATCAA +GTCCGAACGATTGTCGACCACCAGATTCGCTGGTCTGCAATATTCACCCTAGCCCACAAGCACAAATCC +TCGGCGCCGAATATAATCCTCAAGTACTCCAAAGACTCAAATATTGTAAATCAAGAAGGTGGCAAGATC +CTTGCAGAGTTCCCCAACAGCATAGAGCTTGGGAAGCTCGGACCCGGTCAAGACCTGAACAAGAAGGAA +CACTCAACTACTAGTCTAGTCTAG'; cmpthese( $count, { 'regex' => sub { my ( $prematch, $match, $postmatch ) = $seq =~ m{(\A .*?) (CTGGCCCGTAA) (.*\z) }xms; + }, 'matchvars' => sub { $seq =~ m{CTGGCCCGTAA}xms; my ($prematch, $match, $postmatch) = ($`, $&, $'); }, 'matchcontext' => sub { $seq =~ m{(?p)CTGGCCCGTAA}xms; my ( $prematch, $match, $postmatch ) = ( PREMATCH(), MATCH(), POSTMATCH() ); }, } );
[download]

Rate regex matchcontext matchvars regex 17065/s -- -24% -84% matchcontext 22590/s 32% -- -78% matchvars 103806/s 508% 360% --
[download]

In reply to Re^3: Style question: regex versus string builtin function by lima1
in thread Style question: regex versus string builtin function by eyepopslikeamosquito

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