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Perl Lecture Notes - April 12 2002

• Meta-Programming
  Things to think about beyond the code itself
  • Testing
    • Code the Unit Test First
      • XP - Extreme Programming
      • Portland Pattern Repository Wiki
    • Perl's test protocol
      • ok( $assertion );
      • trivial example : testing/test.pl and testing/sqrt.pl
      • You've seen this stuff when you install a CPAN modules.
  • Version control (i.e. CVS)
    • keep track of versions and changes to your code
    • one way : CVS - Concurrent Versions System
    • cvs notes on how to add a project of yours to a cvs server on bob
  • Documentation
    • readme.txt - an overview of what's what
    • POD - interface , or how to invoke it
    • implementation - comments within code
  • Installation
    • develop vs deploy
    • perl scripts to automate copying, setting privileges, etc.

  • Putting it all together to test a cgi script : RegistrarSchedule example
    • run it
    • implementation:
      • CPAN Storable.pm for data persistence,
      • CGI.pm handles parameters passed,
      • single .cgi file with html embedded in long strings
    • cvs repository RegistrarSchedule in bob /home/cvs/msie02
    • source - MarlboroClassSchedule.cgi
    • test.pl
    • install.pl
    • readme.txt

• Writing CPAN-style Perl Modules ...
  by letting h2xs do all the set up for you.
  • So easy it must be immoral or fattening.
  • a step-by-step example

• Inline C
  Putting C code (or Java,Python,Ruby,assembler...) into your Perl source
  • perl and C code - rounding off numbers
  • How it works:
    • Parses C code to find arguments. (Parse::RecDescent)
    • Stores all the XS stuff in a .Inline or _Inline directory.
    • C compilation is slow - but only recompiles if C source changes. (Uses an MD5 hash.)
  •   But wait, there's more!
  • perl to C, Java, and Python in one file: inline_demo.pl
  •   It slices! It dices!
  • another java example: Pantry.pl
  • Windows "alert" box from their system library. Inline C Cookbook: Win23 alert
  • The Inline API
    • What the Inline.pm module really gives you is a general interface to something else from perl.
      Several people have now put a number of other languages in - even assembler.
    • Inline-API - how to add the language of your choice
    • Even Inline::Perl
      (Not quite as stupid as it sounds, since you could have Inline::Perl-4.0, from within Perl-5.6.)

  • A real example - VectorDouble.pm
    • a perl object to manipulate arrays of double-precision numbers.
      Fast, because the real work is done in C.
    • documentation
    • source code
    • I worked on this last year, thinking about how to do numeric work from perl.
    • To see it run, do "perl VectorDouble.pm".
    • To see the documentation,
      do "perldoc VectorDouble.pm" or
      "pod2html VectorDouble.pm > VectorDouble.html".

• Resources
  • perl unit testing
    • Test::Simple - basic utilities for standard perl tests
      • tutorial
    • Test::Unit - unit test framework similar to Java's JUnit
    • libwww-perl - perl CPAN modules for fetching pages
      • lwp-perl cookbook
  • CVS
    • home
    • book - Open Source Development with CVS (chapters explaining CVS are online)
  • Inline
    • Inline.perl.org
      Both the tutorial and cookbook are good.

• Assignment
  • Work on your capstones,
  • And think about incorporating some of this stuff in 'em.

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See you in the third trimester, eh?