Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

The point is that $` with friends slow down every other pattern as well. If you use /p you will still have a comparatively slow match, but it won't effect the other matches.

use 5.010; use strict; use warnings; use Benchmark qw(cmpthese timethese); my $r1 = timethese( -1, { p_before => sub { 'hola juan' =~ /ju/p }, no_p_before => sub { 'hola juan' =~ /ju/ }, }, 'none'); eval '$`'; my $r2 = timethese( -1, { p_after => sub { 'hola juan' =~ /ju/p }, no_p_after => sub { 'hola juan' =~ /ju/ }, }, 'none'); cmpthese({ %$r1, %$r2 }); __END__ Rate p_before no_p_after p_after no_p_before p_before 1067899/s -- -2% -2% -80% no_p_after 1084733/s 2% -- -1% -80% p_after 1091288/s 2% 1% -- -79% no_p_before 5318863/s 398% 390% 387% --
As you see, the pattern with /p and the patterns executed after $` has been seen are equally fast, and that makes sense since they do the same work. The pattern without /p and before $` is however significantly faster, since it does not have to compute the extra match variables.

Hope this helps,

In reply to Re: The /p modifier in Perl5.10 regexps by lodin
in thread The /p modifier in Perl5.10 regexps by casiano

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others browsing the Monastery: (1)
As of 2022-05-22 15:04 GMT
Find Nodes?
    Voting Booth?
    Do you prefer to work remotely?

    Results (80 votes). Check out past polls.