[roch-pm] [Fwd: www.perl.com: Beginners Intro to Perl - Part 3]

[Brian Mathis]

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From: "www.perl.com update" <onperl at lists.oreillynet.com>
Subject: www.perl.com: Beginners Intro to Perl - Part 3
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Hello, perl.com subscribers.

* Perl News

Lots of important work is going on behind the scenes.  Jarkko 
Hietaniemi has been refitting the regex engine to work on UTF8 
strings.  This has been waiting a long time; it was the only major 
part of Perl that still had grossly incorrect behavior for UTF8.  

To understand the basic problem, consider the /./ metacharacter.  
Does this match a single character, or a single byte?  (Recall that 
in a UTF8 string, a character might contain several bytes.)    

The answer is that it depends.  If the regex that contains the . was
compiled in the scope of a 'use utf8' declaration, then it matches a
character.  Otherwise, it matches a single byte.

However, this semantic is at odds with the way the rest of Perl
works.  Consider the 'length()' operator.  Does it return the length
of its argument in characters or in bytes?  It used to have a 
semantics like the regex example above, and depended on the
presence of a 'use utf8' declaration.  The Perl5 porters realized a
while back that this wasn't going to work well.  Instead, each scalar
now carries around a flag that marks it as a plain byte string or as 
a UTF8 string, and the length() operator looks for this flag and does
the right thing for both kinds of data, always returning the length 
in characters.

Now the regex engine has to be converted to do the same thing, and
Jarkko has been doing it.  Parallel to this, Ilya Zakharevich has 
been putting in some long-awaited improvements.

* What's New on the Site

The third installment of Doug Sheppard's well-received series 
introducing Perl for beginning programmers.  In this article, Doug
discusses regexes.

* Coming up

Another article from Simon Cozens about Gnome should be up next week.

Also, we have an article about POE in the works.  POE won the 'Best
New Module' award at TPC3.  It's basically a framework for building
event-driven programs.  For example, if you want to write a network
server, you can use POE, and POE will take care of all the details of
managing sockets and clients and leave you to write a few simple
subroutines that implement the protocol.

Thank you again.  I will be in touch again next week.
 
Mark Dominus
Managing Editor

***

Beginner's Introduction to Perl - Part 3
http://www.perl.com/pub/2000/11/begperl3.html?wwwrrr_20001121.txt
The third part in a new series that introduces Perl to people who
haven't programmed before.  This week: Patterns and pattern
matching.  If you weren't sure how to get started with Perl,
here's your chance!

 
Article: Program Repair Shop and Red Flags
http://www.perl.com/pub/2000/11/repair3.html?wwwrrr_20001121.txt
Once again I take a real program written by a genuine novice and 
show how to clean it up and make it better.  This time we turn a 
perl4 library into a Perl 5 object-oriented module. I show how 
to recognize some "red flags" that are early warning signs that you 
might be doing some of the same things wrong in your own programs.

 
Article: Hold the Sackcloth and Ashes
http://www.perl.com/pub/2000/11/jarkko.html?wwwrrr_20001121.txt
Jarkko Hietaniemi, the Perl release manager, responds to the
critique of the Perl 6 RFC process. 

 
Article: Critique of the Perl 6 RFC Process
http://www.perl.com/pub/2000/11/perl6rfc.html?wwwrrr_20001121.txt
Many of the suggestions put forward during the Perl 6
request-for-comment period revealed a lack of understanding of
the internals and limitations of the language. Mark-Jason
Dominus offers these criticisms in hopes that future RFCs may
avoid the same mistakes -- and the wasted effort. 

 
Perl Conference: State of the Onion 2000
http://www.perl.com/pub/2000/10/23/soto2000.html?wwwrrr_20001121.txt
Larry Wall's annual report on the state of Perl, from TPC 4.0
(the fourth annual Perl conference) in Monterey in July 2000. In
this full length transcript, Larry talks about the need for
changes, which has led to the effort to rewrite the language in
Perl 6.



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