Dermot and I started discussing various topics in this node and I decided it would make more sense to move this to SoPW so more people would see it and it wouldn't be lost forever in Q&A.

So, here are my replies to him -- see the above link for the full context of the conversation.

• I'm a bit embarrased that my first submission to PM went down in flames :)

No need to be embarassed; you didn't do anything wrong. I just wanted to make sure people saw things from all the angles.

• The code referred to uses 'undef $/' to facilitate the slurp. I should have included this in the example. I take it only fully valid running code should be posted here. I'll do that in future.

No, I wouldn't say fully valid running code is necessarily required, but I do think something like the value of $/ is important info. It seems like just a minor oversight though; definitely not a big deal.

• Why is binmode dubious ? I agree that [^>]* is a much better choice for the regex.

Well, why is the binmode there? An HTML file is a text file, not a "binary" file. I'm no Windows programmer, so I can't say for sure, but I'd think that using binmode on an HTML file would be a bad idea. And I certainly can't see it serving any purpose here.

• Showing my ignorance. What is re 'debug' ?

re is a pragma in the core distribution, and one of the options to it is `debug'. If you `use' it in a program, it will verbosely tell you how the Perl REx engine does its matches.

Here's an example of how you might use it:

[~] $ perl -Mre=debug -we'$_ = "abbaba"; /(.).*?\1/'
Freeing REx: `,'
Compiling REx `(.).*?\1'
size 11 first at 3
   1: OPEN1(3)
   3:   REG_ANY(4)
   4: CLOSE1(6)
   6: MINMOD(7)
   7: STAR(9)
   8:   REG_ANY(0)
   9: REF1(11)
  11: END(0)
minlen 1
Omitting $` $& $' support.

EXECUTING...

Matching REx `(.).*?\1' against `abbaba'
  Setting an EVAL scope, savestack=3
   0 <> <abbaba>          |  1:  OPEN1
   0 <> <abbaba>          |  3:  REG_ANY
   1 <a> <bbaba>          |  4:  CLOSE1
   1 <a> <bbaba>          |  6:  MINMOD
   1 <a> <bbaba>          |  7:  STAR
  Setting an EVAL scope, savestack=3
   1 <a> <bbaba>          |  9:    REF1
                              failed...
                           REG_ANY can match 1 times out of 1...
   2 <ab> <baba>          |  9:    REF1
                              failed...
                           REG_ANY can match 1 times out of 1...
   3 <abb> <aba>          |  9:    REF1
   4 <abba> <ba>          | 11:    END
Match successful!
Freeing REx: `(.).*?\1'
[download]

-dlc

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