I first used Perl in 2002 - about 10 years ago.  Over the years, I have continued to dabble in it but often felt that stuff like Mason and mod_perl were a little beyond what I needed to achieve.  So I stuck with a Perl/CGI format when writing web pages.  A recent post persuaded me to move forward from there - that is a work in progress.

So, after 10 years, why go to Modern Perl for Non-Perl Programmers held by Dave Cross @ Perl School? 

(I  will confess I was a little concerned I'd be taking a place that could be used by someone else but I am glad I went.)

Dave started with a walk through the basics of Perl, sigils, arrays, hashes and lists.  Most of this I had encountered before, but, back when I just started Perl, I got confused between the use of (), [] and {} and what a list actually was.  As a result, I ended up with some fairly interesting results trying to define hashes, arrays and access the elements and key value pairs within.

I came from a C programming background; web and mail server work so I was used to strongly typed languages.  With some languages you can have really mad hard typing; you can declare two integers on two separate lines and then get the compiler to consider them of different types - even though they are both integers.  Before that I'd been in engineering software, FORTRAN mostly but some C and even BBC Basic.

So Perl is a loosely typed language, identifying variables more by some form of structure than by type.  Fine.  Having Perl categorised as a loosely typed language really helped me feel Perl was a little more solid.

Solid is useful.

Then we got onto arrays and hashes, neither of which I had misunderstood, although, back in 2002 it was the first time I had encountered associative arrays - but I'm glad the Perl community has decided to call them hashes. 

Not least, because hash is a lot easier and quicker to type than associative array.  4 chars as opposed to 16.  (Another Perl habit - less typing == good.)

So .. hashes and arrays.  Originally, I had a hard time remembering where to use the (), [], and {} with hashes and arrays.  One part, accessing an array element or a hash key value pair was easy - $arr[$index] for arrays and $hash{key} for hashes.

The next part, defining hashes and arrays wasn't so easy and in my early years I used to use () to define an array and {} to define a hash.  Then I would have problems accessing hash key value pairs and never quite understood why.

Today

#!/usr/bin/env perl

use Modern::Perl 2011;
use autodie;

my %hash = { fred => 'wilma',
          barney => 'george'
          };  
say %hash;
say $hash->{barney};

Global symbol "$hash" requires explicit package name at ./test.pl line 11.
Execution of ./test.pl aborted due to compilation errors.

say $hash->{barney};
to 

say $hash{barney};

Reference found where even-sized list expected at ./test.pl line 6.
Use of uninitialized value $hash{"HASH(0x111d998)"} in say at ./test.pl line 10.
HASH(0x111d998)
Use of uninitialized value in say at ./test.pl line 11.

my $hash = { fred => 'wilma',
          barney => 'george'
          };