[Purdue-pm] Meeting Post-Mortem and Challenge

Dave jacoby jacoby at purdue.edu
Tue Oct 19 12:10:58 PDT 2010

We had a selection of new faces at our Perl Mongers meeting, seeking to 
learn Perl to understand and adapt the tools they have at hand to their 
further purpose. Mark and I and mostly Rick went through an example 
program they had used, RADpools, as a teaching tool, covering many of 
the basics and some of the advanced elements of our favorite programming 
language, until we got to line 143.

             foreach my $mid (@pool_mid_list) {
                 $mid_length = length $mid;
                 if ( !$fuzzy_MIDs ) {
                     push @{ $mid_pools{$mid} }, $pool_name;
                 else {
                     for my $i ( 1 .. $mid_length ) {
                         for my $base (qw{A C G T}) {
                             my $fuzzycode  = $mid;
                             my $prebase_i  = $i - 1;
                             my $postbase_i = $mid_length - $i;
                             $fuzzycode =~ s{^([ACGT]{$prebase_i})
                             push @{ $mid_pools{$fuzzycode} }, $pool_name;

And, actually, the if(!$fuzzy_MIDs){} section is straightforward. The 
else{} section is ... well, something else.

Specifically, it's the kind of regular expression that causes folks like 
JWZ to say "now you have TWO problems". Rick specifically mentioned that 
he would not use regular expressions for this problem, and Mark said it 
was best to ignore my attempts to explain this.

	(I will point out now that this code is
	copyright 2008,2010 by John Davey of the
	University of Edinburgh and
	is licenced by the GPL v3.)

I think that a good challenge for our November meeting would be to come 
up with variations of the else{} code that are more suitable for Perl 
101. Does that sound good to anybody?

Also, I have just reserved WSLR116 for next Tuesday from Noon to 2pm to 
continue the analysis of RADpools.

Dave Jacoby                         Address: WSLR S049
Code Maker                          Mail:    jacoby at purdue.edu
Purdue University                   Phone:   765.49.67368

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