Re: [MacPerl] Wildcard

[Matthew Langford <langfml [at] eng [dot] auburn [dot] edu>]

On Wed, 23 Sep 1998, Brian McNett wrote:

> I'd recommend a good book on regular expressions (I think there's one out 
> by O'Reilly).  The camel and llama books don't really say very much on 
> the subject, or give more that a hint at how important it is.

I disagree with this.  While the treatment in the Camel book is not
book-length (twenty-something pages devoted to the initial introduction),
they succinctly summarize the features and operators and options.  Then,
to flesh out the understanding, you have the bajillion examples in the
rest of the book--one of which is very likely to do exactly what you were
looking for.  

For example, on page 27, right after starting to talk about REs, a snippet
of code with this construct
  if ($line =~ /http:/) {
      print $line;
  }
is given and explained carefully.  Cha-ching!
Then, it's shortened in the next paragraph to 
      print if /http:/;
after explaining about the ubiquitous $_ variable.  TMTOWTDI, ya know.
Ba-bing!

In addition to this, starting with the Camel gives you the exact syntax
needed by Perl; for example, knowing how to bind searches to a variable,
escaping Perl key values, the pitfalls of m//o, the possibilities of m//x,
and variants such as tr//, s//, and so on.  Without bothering (too much)
about the computational complexity of REs.

> if ($text eq "t*") {print "$text\n"} # Where * is a wildcard
becomes 
    print "$text\n"  if  $text =~ /^t/;

Maybe the book on REs is useful if you can't grok the explanation in the
Camel book, or maybe if you want to obsess on endless flavors of REs, but
to learn REs in Perl, I'd start on the Camel.  You get the context and
balance of when to use a regex from the Perl arsenal of tools.  

On the other hand, if you are constantly encountering regexen (reggae?) in
a flood of Unix tools like perl, grep, awk, sed, sendmail configs, m4
macros, and on and on andonandon, you may want a generic, broad and deep
coverage of REs.  Then buy the O'Reilly RE book. 

"The Camel" = Programming Perl, 2nd Ed.  by Larry Wall, Tom Christiansen,
and Randal L. Schwartz, O'Reilly Books, ISBN 1-56592-149-6

Since this _is_ a MacPerl list, I should also mention the MacPerl: Power
and Ease book, which is more natural for Mac users, since it gives
examples of Perl in the context of MacOS.  And it explains how to generate
a Mac-like user experience using the Toolbox from MacPerl.  Others have
given the ISBN for it, and have had far more intimate contact with it, so
I'll kindly shut up. 


--
MattLangford 



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