The aim of this tutorial is purely to introduce you to Kylix. In most ways, Kylix is pretty much identical to Delphi, so you'd think that there wouldn't be much to say. You'd be right, but there are still some things to take into consideration that you may not be aware of, and this tutorial goes over them. Where possible this site has now been made compatible with all things Kylix. In practice this means that all the non-DelphiX tutorials and their source code, will work with both Delphi and Kylix.
So, in terms of the actual interface, you'll see very little differences from Delphi. Everything is where it should be, the only thing worth mentioning here is that when you make alterations to Properties in the Object Inspector you should get into the practice of pressing Return after you make each alteration as Kylix will forget anything you've entered unless you do so. You can also just select another entry instead which will have the same effect, but if say, you just go to the Object Inspector to change the Name property, you need to remember to press return before you get back to altering code, or whatever. It's quite possible that many of you do this already so this won't be a problem for you, but if you're like me - take note ;-)
So far so good, but when it comes to reusing your old Delphi code, things get a little more complicated. As long as your actual code doesn't use any instructions specific to the Windows environment, it'll work fine. In most cases, you'll be fine then. But, before you actually can get your existing code to work you do need to make alterations to the uses section of your code in both your unit's source and your project's source. Let's go through these changes now then.
The 17th letter of the alphabet
Unfortunately, in Kylix most of the entries in your uses section will be useless. Let's take a look at the code generated by Delphi and Kylix when you first start a new application:
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;
SysUtils, Types, Classes, Variants, QGraphics, QControls, QForms, QDialogs;
The first two entries of the Delphi Code - Windows and Messages, are specific to Windows. SysUtils on the other hand will work for both Windows and Linux, as will Classes. It should be clear to you the similarity of the rest to each other. Simply adding a Q at the beginning of an entry here, does the trick. The same applies for other such entries that exist once you've added components. Menus in Delphi is QMenus in Kylix, and Buttons in Delphi is QButtons in Delphi, for example.
Due to these restrictions, you have the option of just making your Delphi application Kylix-compatible by changing the relevant entries so that they now work in just Kylix, or we can go for the better option of making our code work in both. We can do this with the following code:
Windows, Messages, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, ComCtrls, Buttons,
QGraphics, QControls, QForms, QDialogs, QStdCtrls,
QExtCtrls, QComCtrls, QButtons, Types, QTypes,
This takes the most commonly used entries and allows your game to check at compile time whether you're using Windows or Linux, choosing the relevant entries. You may need to alter this list depending on what you're doing. If you're lucky enough to have Delphi 6 Professional or Enterprise then the above will not be needed at all because any new code made with either of these two products, includes such information.
We still have to modify our Project source now. To view the source of your project you need to go to 'Project' on the menu and select 'View Source'. This brings up the source for our project where we can edit our uses section. You need to modify the following code:
So that it is:
This has a similar effect to that which we've done already but you should make sure you don't modify the line that follows this code, as it tells your project where to find your unit source.
The next thing we need to bare in mind before we can run our program effectively in both Delphi and Kylix is that Linux is case sensitive when it comes to file names. This means that Unit1.pas is different from unit1.pas so you need to make sure that at all times you're linking to the correct file. What this means for your existing code is that we need to modify one line in our unit source and one line in our project source.
As we're already viewing our project source, we may as well start there. You'll notice the following line before the begin line:
Notice that the .RES bit is in capital letters. The problem here is that the actual res file that your project will create (in both Delphi and Kylix) will have a lower case extension. This doesn't matter in the land of windows where case sensitivity isn't an issue, but with Linux it needs to know that it is lower case, so change it to:
This will still work for Windows, so you can keep both operating systems happy. You may find that when you change this line to lower-case that it brings up a warning, saying that the .res file has been recreated. Just click OK and continue on and everything will be fine! Anyway, if you now go back to your unit source, you need to change a similar line which looks like the following:
You'll find this line just after the implementation line in your program listing and as before, you should change it to the lower case - .dfm so that Kylix recognises it.
That's everything you need to know to at least start making your code Kylix-compatible. More complicated programs may need additional alterations, but they should on the whole be pretty straight forward.
Before I leave you to it though, here's a couple of things to bear in mind when coding. You may have heard about how Linux hardly ever crashes and it's as solid as a rock. For the most part this is true and you'll probably find that Linux itself is never a problem. Kylix though will most probably crash more often than not. There's a number of reasons for this, but the primary reason is that it does make partial use of the WINE software which allows windows applications to run in Linux. As Kylix hasn't been made from the ground up in Linux, this causes some instability. You're probably pretty used to this anyway if you've been using Delphi for any length of time. At least when Kylix crashes it tends to come up with a warning message, suggesting you restart it - when did you ever see Delphi admit defeat like that? ;-) So basically, save often to make sure you don't lose your work!
Another point to bear in mind is that Kylix appears to be a bit more sensitive to sloppy programming. If you're getting funny errors in your programs make sure that you've put lines in exactly the way the online help suggests. A case in point here is the Randomize; line. When I originally wrote the tutorials for this site which made use of this function, I made the mistake of declaring this line more than once in my program. In fact, every OnTimer event called it again. This doesn't seem to matter in Delphi, but if you try it in Kylix, the randomisation tends to be very slow. A look at the online help for both Delphi and Kylix tells us to only declare this once in our programs, so simply moving this line to the FormCreate procedure sorts this out. I'd bet that there are other such functions that will make a fuss in Kylix, that didn't in Delphi, so watch out ;-)
Okay, so get coding in Linux. If you get stuck let me know through either e-mail or the message board, and if you think I should mention something else that you've come across, let me know. Incidentally, if you're looking for a good reliable Linux distribution, I'd really recommend Mandrake. It's what I use, and it's very up to date and has a lot of support. It's up to you though! Bye for now.