New tutorial online

A new instalment in my loose series of tutorials on OS4 user interface programming can now be found on OS4coding.net, this time with a full working C code example. Enjoy!

Thank you very much,

very instructive tutorial.

We sure do need good C programmers, i could not resist though:

a Gui4 Cli look alike

@Trixie
New article also pretty interesting. Few more articles of this kind, and we can make a os4-progamming-book at last

@ kas1e
Quote:

Actually, the material for my articles comes from the sketches I wrote for the OS4 Programmer's Guide (which unfortunately never took off).

Thank you. Tutorial are always welcome. Keep up with the good work.

Really a pitty. Any chance to release some pre-version of your tutorial to public?

Good job, Trixie, keep 'em coming!

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Isn't that what he is doing already?

Best regards,

Niels

I have been studying the example and have some questions about declaring structures and opeing libraries;

- at line 40/41 i read ( not in 'main')
struct Library *IntuitionBase, *UtilityBase;
struct IntuitionIFace *IIntuition;
Why is it not needed to declare *IUtility here ?

- more generally: why not declare all used structures (in a one-file source) at the beginning? Seems easier to maintain using such a standard, or are there reasons not to ?

@JosDuchIt
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Because the example does not call any Utility Library functions. The library is opened to provide the hook functionality but you don't need the interface unless you want to use the library's functions yourself.

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What exactly do you mean?

@JosDuchIt

Depending on how you compile your program.

You don't need to open and close libraries and you don't need to declare the interfaces, Just include the proto types.

Compile your program whit

GCC myapp.c -o myapp.exe -lauto

if you don't like to type IExec/IDOS in front of every exec command, you can type

GCC myapp.c -o myapp.exe -lauto -D__USE_INLINE__

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No, don't do that when using ReAction for GUI. Read the first tutorial, section 2.3.

@trixie
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I think an erroneous read of your source made me miss some declarations (besides IIntuition) As i missed IIntuition and thought others were only declared in main or in the functions, i was wondering in which cases there is an advantage to do that. I did not see one, but then some parts of C are really puzzling to me.

@JosDuchIt

I always prefer declaring local variables for data that is not needed throughout the entire lifetime of the program. A good example is the pointer to the Intuition window: you'll see in the tutorial example that instead of declaring and keeping one global variable, the struct Window pointer is declared three times locally (inside the functions) and is obtained from the window object when it is needed. It does not have any particular advantage in this example but avoiding globals is good coding practice because it is generally safer.