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Saturday, March 18, 2006

What's wrong with Perl

It can be a refreshing tonic of a language when you move to perl
from something like basic, C or Java.
Perl can do what tens of Unix tools such as sed and awk can do from
the shell, but with more flexibility and higher order data structures
such as the perl 'hash' or 'associative array'.
You can sit and evolve a perl one-liner of X hundred characters
that will find and process millions of lines from thousands of files
from within hundreds of directories.
When you want to know how to do something else there is The Camel
, either the book or that human store of Perl Knowledge on the next
floor, a few cubicles over.
Before long, you have amassed a large personal perl knowledge
base, and can tackle most of your tasks, without having to consult
The Camel. You become more confident in perl and start to code for
others in your team, and write scripts in files rather than one
liners.

WAKE UP!

Languages have moved on.

Do you use perl references? Happy with them? Do you know that you
can get all that power without all the reference-gymnastics. Indeed,
you can get more power as you are freed from the mundane “how
do I create and use a hash of hashes”, to “O.K. The data
naturally starts as a hash of hashes so...”

Perl subroutines. Even AWK, one of the Unix stalwart languages
that perl was created to supplant has named arguments to its
functions. The better scripting languages can do a lot better,
allowing you to pass two lists into a function as easily as passing
in two integers. Or to return three hashes just as simply.

The perl slogan “There is more than one way to do it”
is often cited as one of perls strengths, and used by many
perl-mongers as their reason to stick with it. But how many of you
actually mean the extended form: “There is more than one way to
do it, and mine is the best”, or, “There is more than one
way to do it, but you will use mine!”, or more likely: “There
is more than one way to do it, and I don't know yours”, or
“There is more than one way to do it, and you will learn
mine!”, or “There is more than one way to do it, but I
don't know how to find any of them in Camels index”.

Perl still has goto! (and in its most evil of forms too, the
computed goto: where you have to interpret the program in your head
to work out where the goto might jump to from the listing because the
goto target is the result of an expression).

So much of perl documentation reads like 1001 recipes for using
1001 features, without any central theme to shape them.

Being an engineer, I am trained in finding patterns and
extrapolation. It is much easier for me to learn a small set of
powerful rules with a straightforward way of combining them. Perl,
unfortunately has a large number of 'gotchas' that bite when you try
to venture out from the recipes and examples given.

Conclusion

If you know perl, and have a need for programs greater than a few
tens of lines of code, then you should invest a week or two of your
time learning a different dynamic language. In that time, put aside
your perl knowledge and try to not just use the other languages
syntax, but learn how things are naturally done in that language.
Nothing may beat the 'perl -p -i -e' one-liner, but proper function
parameters and strict typing may be better for your longer scripts.

If you are thinking of learning Perl then think twice. Perls
'sweat-spot' is much diminished as new dynamic languages have emerged
with a less tacky support for new methodologies and standards such as
object oriented programming, program maintenance, functional
programming, XML, multi-language programming, and programming on
multiple frameworks such as dot-net and the Java Virtual Machine.

END.




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