Perl training: Net-Innovation Finland Oy
Sivut Suomeksi  Pages in English 

Perl services
   Perl training overview
   Commercial Perl support

Perl classes
   Introduction to Perl
   WWW/CGI programming
   Advanced Perl

Perl kurssiaikataulut
   Hewlett-Packard

Yleistitetoa Perlistä
   What is Perl ?
   Articles, links
   Perl's home page

Company information
   General information
   Contact information

Feedback
   anders.lundstrom@niv.com
   Net-Innovation Finland Oy

What is Perl ?

General background info about Perl:

Perl today is an very versatile tool being used for a large number of different tasks including system administration, web programming, database programming, general software development, text-manipulation, socket-programming etc. People not only write simple scripts but also develop very large programs in Perl and this is feasible with the object oriented features that Perl currently supports.

One of the major strengths is the portability, virtually all operating systems support Perl with the major ones being Unix and Windows. Most courses I have taught have used Windows (XP/2000/NT) as the platform and it has worked very well indeed. Clearly today there are no good scripting languages bundled with Windows and those available (VisualBasic etc) are unable to address the typical system administration tasks that your are facing on Windows. Perl among other tasks is addressing this niche quite well: a number of NT specific extensions ("modules") have been developed that lets you administer users, printers, registry, events etc on Windows. On the other hand, Unix was always strong with shell-scripts but the traditional shell scripting approach is far from ideal when you have to write something that is slightly more complex (or something that cannot be allowed to end up as "spaghetti-code").

The biggest reason for Perl's recent popularity is Web-programming: O'Reilly has estimated (in 1998) that ~90% of dynamic Web-pages are generated with Perl. Perhaps that figure is too optimistic but is very evident that Perl is a popular language for backend Web-application programming. Accordingly, lots of useful modules have been developed that make CGI/Web-programming very easy.

Often closely related to Web-programming is Database-access: eg you can write a Perl Web-application that runs on Unix talking to Oracle and move this to NT talking to Informix without changing a single line of code. In addition the abstraction level is very high, one example I use in class: a C-SQL application is 400+ lines of code, in Perl it is 9 lines of code.

Web-client programming is also an interesting application: you might want to regularly download stuff from the Net (such as a mailing list archive), check your WWW-links, mirror Web-sites etc. Perl has high-level modules for this purpose as well, eg it takes a 2 line program to write an application in Perl that download a given url and writes it to a file. I use several Perl Web-clients in my own environment that are essential for how I use the Internet more effectively.

Perl 5 that came out in 1994 introduced the concept of modules: extensions to Perl that embed significant functionality in a well-tested piece of code that can be reused over and over again Currently about 10000 modules are available that help you in virtually any kind of task you can imagine. And as Perl itself, they are free and come with the source code. Some examples: Database, Web (client/server), Network-client (FTP, Telnet, NNTP etc etc), System-Admin (eg Windows specific extensions), GUI-programming (portable graphical user interfaces between Windows and X/Motif), Security etc etc.

To summarize, in my opinion the main advantages with Perl are in addition to the points mentioned above:

  • easy to get started, also targeted to people who are not professional programmers
  • very fast development cycle
  • lots of Perl developers (1-2 million)
  • cross platform support (Unix, Windows (XP/2000/NT/W98/W95), Mac, OS2, DOS, VMS, MVS, MPE, Amiga etc)
  • very strong in text-manipulation, also supports binary data (unlike shell scripts)
  • source code debugger (in contrast to traditional shell scripts), profilers and other development tools, even free GUI builders
  • supports Object Oriented development and advanced data structures. In fact all the recent significant modules use OO techniques in order to facilitate better reusability.
  • access to object-code written in C/C++, used by most major modules such as databases, X/Motif and Windows extensions etc.
  • support: the Internet provides an excellent support channel with active newsgroups (~1500 messages / week). Commercial support also available.
  • security: Perl contains some unique facilities to write secure applications, especially useful in CGI/Web applications
  • a large number of high level modules are available
  • it is FREE. This applies both to Perl and all the 3800 modules on the so called CPAN (Comprehensive Perl Archive Network)
  • it is FUN ! Perl is the most enjoyable environment I have worked with so far and an environment (unlike C) where you essentially force the computer to think like a human and not the human to think like a computer... Think about a simple thing like copying an array in C: you have to express this to the computer in a "HOW"-fashion (allocate memory, move the pointer, copy one element, move the pointer, copy the next element...) instead of saying the "WHAT" you want to do as you can do in Perl: @x = @y (@ is symbol for the array). Perl will take care of all the nasty details for you: allocate memory, copy the elements etc.