Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
My rule of thumb: if a function doesn't make code any easier to read, it's not worth writing.

At one point in my life (not very long ago ;)), I had the temptation to create lots of little 2-line and 3-line functions (probably coming from an OO background in school, where I was taught to make even simple variable accesses into object methods...)

But, consider the following code:

# test1.pl (uses no user-defined functions): for($i = 0; $i < 100000; $i++) { print $i; } # test2.pl (uses a simple function): for($i = 0; $i < 100000; $i++) { print func($i); } sub func { return $_[0]; } # OUTPUT [falkkin@shadow ~/perl] time perl test1.pl > /dev/null real 0m4.826s user 0m4.240s sys 0m0.010s [falkkin@shadow ~/perl] time perl test2.pl > /dev/null real 0m14.227s user 0m14.100s sys 0m0.050s

It's clear in this case that the overhead involved in calling a function (mostly involving pushing variables to perl's stack and popping them back off) makes the code run roughly 3 times more slowly. Generally, I try to avoid calls to "small" functions in inner loops whenever performance is anything of an issue; if I'm only reusing those few lines of code once or twice in a program, it's just not worth it to create a function for it, in my opinion.


In reply to Re: When do you function? by Falkkin
in thread When do you function? by zdog

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



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

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

    How do I use this? | Other CB clients
    Other Users?
    Others imbibing at the Monastery: (8)
    As of 2014-10-21 00:30 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      For retirement, I am banking on:










      Results (94 votes), past polls