PerlWiz - Frequently Asked Questions
/ Troubleshooting

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This page accumulates a number of frequently asked questions and troubleshooting questions that are asked of the PerlWiz application.

Sections are as follows:-

General

The O'Reilly books (http://perl.oreilly.com/wheretostart.html) are generally considered to be the best place to start with Perl. The cookbook is popular for people who want to get something specific done in Perl and have some programming experience already. "Learning Perl" is a good general place to start for most people.

If you have a look at the links section on the PerlWiz web site, there are a number of on-line tutorials designed to get you started, and some go into a lot more depth.

If you want to use Perl with a product like PerlWiz, you need to download the ActiveState Perl tools. Full details are given in the installation help pages supplied with PerlWiz. The PerlWiz IDE will automatically detect when and where you've installed the ActiveState tool set and make use of it after you've installed it.

Perl is essentially an interpreted language, although it is possible to pick up Perl compilers (or sometimes programs that convert Perl to C in order to compile it). However, as this can be slow for web applications in particular, various techniques have been developed where the program is compiled into an intermediate symbolic code and stored in a web server so that it can be quickly executed many times - Apache web server integrates particularly well with something called mod Perl (this integration has a number of other fringe benefits too). PerlWiz has its own integrated web server that simulates the working of a web server, so that you can output HTML pages from a Perl program, and see what they look like in a web browser - even to see how forms operate etc. So you don't need a separate web server to run Perl-based web applications within PerlWiz.

There are various tutorials within PerlWiz to help you get going with a number of different projects - e.g. simple console input / output, debugging, working with web forms / web pages, creating a database application with Perl and MySql etc.

 

You're not alone in this.  Everyone who learns a new skill - be it computer programming, learning a foreign language, learning mathematics, learning to drive a car etc. etc. has the same problem.

The truth of it is it is not easy, and it takes a lot of Persistence and determination, especially when you are doing it without the insistence of a teacher, or have to hold down a job at the same time!

The best way of learning is to try things out. I always found it easier to tackle changing a program somebody else had written, to do other things - e.g. add features, change the way it looks / operates etc. It's much easier to start from a base-line like this, And the reality is that most real programmers work like this anyway - They shamelessly steal each other's programs and adapt them to work the way they want. Why reinvent the wheel when the design's mostly there anyway? I admit it! I do it in my everyday working life!  Within the same company, there's no copyright problem anyway, and with a lot of Open Source / Freeware you can work on existing code in this way - PerlWiz is based on various such components.

Also, working this way, you can see your results quicker, and it gives you a real sense of achievement.

So if you are looking to solve a problem, don't think you have to memorize the solution and come up with it from scratch! Find a similar solution and adapt it to your needs. Make sure that you aren't breaking any license agreements before you do this. Otherwise, it's the way most people learn most quickly.  Making small changes lets you explore the language interactively, so you can concentrate on small projects or mini-projects at a time.

When you've done this a few times, you'll start knowing where to look to find your "template solutions" and you'll soon get quicker and quicker at producing a solution.

The traditional "write a program to do this from scratch" way of working Is outmoded, and doesn't fit today's lifestyle. When I teach students from my web pages, most people copy and paste.  One or two don't, as it gives them the chance to digest what's going on as they type.  It doesn't appear to give them a great advantage, though.  It's the trying it out, and playing around with it that helps people relate the code to the effect.

Anyway, hope this helps. The internet is full of examples of code for many different languages, including Perl.   Dip in and try them out.  Look at the help on different commands you don't understand and read up as you go along so you learn a bit more than you anticipated.  Try things out, even if they look a mess initially.  It doesn't matter. You're experimenting. Give yourself time.

And remember... You never stop learning.  I have been programming since I was eleven years old - that's twenty years now - and I can honestly say that I am constantly learning, and feel like there's always a million times more than I know to learn. I just have to pick what I learn carefully to match my current / near future interests and aspirations.

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Debugging

As illogical as it may seem (!), you type your information into the Text Output tab. As you type (in case you wish to type out something in response to a prompt).  Your input appears as highlighted text after any output text. When you press the Enter key the highlighted text is sent to the Perl session as keyboard input (complete with the press of the Enter key - which is how it would work if you typed it directly into a console window). For a full explanation of how this works, see the tutorial on keyboard input.

- Thanks to Jerry for this question, May 2003

N.B. If you are inputting into an array, then you will need to terminate input by pressing Ctrl+Z on the keyboard. This only works in 5.6 of ActivePerl - 5.8 ignores the key-combination.

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Web Server

This probably means that you have the cgi-bin directory set incorrectly. Go into the Project > Properties > Web Server >> CGI (eg. Perl) page and under CGI-BIN (Perl Programs) Root, put the directory where your Perl files reside as the base path. You can then refer to any files in this directory as /cgi-bin/filename in your HTML documents. Or you can leave the directory blank, and just make sure all files are in the same directory as your project (if using the default project, this is the projects directory under your PerlWiz installation directory). You can of course have subdirectories within the cgi-bin folder in order to organize more complex CGI projects. 

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This Page was last updated: 27 June 2004 06:04