mjd-perl-pm on Tue, 16 Apr 2002 08:40:56 -0400


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Perl Tutorials "Program Repair Shop" and "Iterators and Generators" 28-29 May 2002


This year I'll be doing three tutorials at the big Perl conference in
San Diego.  Two of them are new.  As in previous years, I need to
practice these before I go to San Diego, so I'll be giving both
tutorials in Philadelphia next month.

If you were to attend in San Diego, you would pay about $320.  But you
can come to my practice sessions for less than that.  I will ask for a
(voluntary) donation of $5 at each class to cover expenses.  This
request does not apply to Penn students, staff, or faculty.

WHEN

"Perl Program Repair Shop and Red Flags" will be held on Tuesday, 28
May.  "Programming With Iterators and Generators" will be held on
Wednesday, 29 May.  Both tutorials will start at 6PM and end around
9:30 or 10:00 PM.  They will be held in Heilmeier Hall (room 100,
formerly Alumni Hall) in the Towne Building at University of
Pennsylvania. (Directions below.)

WHAT

Perl Program Repair Shop and Red Flags

This is not the same class as last year; it's a revised version with a
substantial amount of new material.  Be forewarned that some of the
new material may be material that I did at last year's practice session
and then cut out of the class before the conference, so there may be
more overlap with last year's practice session than with what was
actually presented at last year's conference.  On the other hand, some
of the repeated material is stuff I added in response to comments I
got at last year's practice session, so maybe it all evens out.

Here's the brochure description:

        PERL PROGRAM REPAIR SHOP AND RED FLAGS II

        You've probably been working too hard when you program,
        writing twenty lines of code when you only needed ten.  But
        there is a better way, and I will show it to you.  You'll
        learn how to improve your own code and the code of others,
        making it cleaner, more readable, more reusable, and more
        efficient, while at the same time making it 30-50% smaller.
        Smaller code contains fewer bugs and takes less time to
        maintain.

        This class expands on 'Repair Shop I' but is independent of
        it, with little overlap.  We'll see more red flags and more
        common errors.  I'll take a complete CGI tic-tac-toe
        application and reduce its code by half without removing any
        functionality or introducing any bugs.  All code guaranteed
        authentic!

        Participants are encouraged to submit their own code for
        anonymous review in the class.  (Send it to
        mjd-tpc6-repair2+@plover.com.)  Class content varies depending
        on submissions, but is sure to include some of the following
        topics:

        Structural vs. functional code
        Elimination of structure
        Boolean values
        Programs that take two steps forward and one step back
        Programs that are 10% backslashes
        print print print print print
        C-style 'for' loops
        Loop counter variables
        Array length variables
        Unnecessary shell calls
        How (and why) to let 'undef' be the special value
        Confusion of internal and external representations of data
        Tool use
        Elimination of repeated code with higher-order functions
        Learning to use a hammer
        The 'swswsw' problem
        Avoiding special cases
        Using uniform data representations

The brochure description for 'Programming with Iterators and Generators':

        PROGRAMMING WITH ITERATORS AND GENERATORS

        Sometimes you'll write a function that takes too long to run
        because it produces too much useful information.  A search
        function might locate ten thousand matches.  A database query
        might return ten million records.  What can you do?

        Perl provides a simple and familiar model for dealing with
        such problems: The filehandle!  Instead of reading every file
        in one giant gulp, we can use filehandles to staunch the flow
        of information, trickling it into the program in manageable
        gulps.

        In this class, we'll see several important modules, such as
        File::Find and DBI, which use this approach.  We'll go inside
        these modules and see how to implement filehandle-like data
        structures and objects ourselves.  We'll see how to write
        functions that suspend themselves and then pick up later where
        they left off.  We'll learn how to take long-running slow
        functions and convert them into speedy filehandle-like data
        generator objects.

        This fundamental technique is a mainstay of programmers in
        other languages, but isn't as well-known as it should be.
        You'll be amazed at how many difficult problems become simple
        when you unleash the power of filehandles.

            Introduction:
                Filehandles are Iterators
                Iterators are Objects
                Common Examples of Iterators: readdir, each, and DBI
            Homemade iterators
            Examples
                File tree scanning
                Permutations
                Genomic Sequence Generator
                Filehandle Iterators
                A Flat-File Database
                Searching Databases Backwards
                Random Number Generation
            Alternatives to Iterators
            Filters and Transforms: 'map' and 'grep' for iterators
            Recursively-Constructed Iterators
            The Semipredicate Problem
            Alternative Interfaces to Iterators
            An Extended Example: Web Spiders
            Converting slow recursive functions to iterators


WHERE

The Towne Building is located at 220 South 33rd Street in Philadelphia.

For directions to the University, see

        http://www.upenn.edu/admissions/undergrad/visiting/directions.html

Maps are available at
        http://www.seas.upenn.edu/staff/pem.html


HOW

Unlike in past years, we have essentially unlimited space, so
reservations are not required; just show up.  

However, if you want to receive the class handout materials, if any,
you should reserve copies in advance.  To reserve materials, please
send an email message to

        mjd-perl-practice-2002+@plover.com

Don't forget to say which class or classes you plan to attend.

Please circulate this notice to any people or mailing lists that you
think might want to see it.

My profuse and heartfelt thanks to Chip Buchholtz and to the
University of Pennsylvania School of Engineering and Applied Science
for providing the space and AV equipment for these sessions.

Mark-Jason Dominus 	  			                 mjd@plover.com
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