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Re: Regex Misuse

by jepri (Parson)
on May 14, 2001 at 11:41 UTC ( #80157=note: print w/replies, xml ) Need Help??

in reply to Regex Misuse

The goal was to extract $width amount of characters from a variable. More experienced programmers are shaking their heads right now, they know it would be much more efficient to use this: substr($someVar,$offSet,$width)

And unpack would be even better yet.

I didn't believe in evil until I dated it.

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Re: Re: Regex Misuse
by kal (Hermit) on May 14, 2001 at 14:51 UTC

    I thought it was funny how he first labelled one way of doing things as a 'mistake', and then proceeded to make the 'mistake' himself:

    if ($text =~ m/\.txt$/)

    Why not use substr ($text, -4, 4); to extract the .txt, and then eq to compare it?

    The reason is, of course, that we write code for readability, not efficiency, for the most part. See "obfuscation" :)

      Well, what I said was that
      could be better written with substr, and still be readable. I have seen from replies to my post that unpack is better yet. I just made the $text =~ /\.txt$/ regex example up as I was writing the post, so it my not be the best, but the point I wanted to get at is if you don't need to match the whole string, then don't. For example:
      $text =~ m/.*$endPat$/
      can be better written (and still readable) as:
      $text =~ m/$endPat$/
      And as you have pointed out, the above code can be written this way (much less readable, I wouldn't recomend using this)
      substr($text,0-length($endPat)) eq $endPat
      On a last note, I never said it was a mistake not to use subst(), I just wanted to point out that in some cases it is better than using a regular expression.

      The 15 year old, freshman programmer,
      Stephen Rawls

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