Emad Al-Bloushi wrote:
> Peace be upon you all,
>
> I'm new to Vala programming language and I have well experience in Java & PHP
> programming languages using OOP , honestly I'm little bit concerned about
> list of issues I hope you can help me to reach the right direction as listed
> below :
>
> 1) How can I list installed packages to compile my code "pango , cairo ,
> gtk+-2.0 ..etc" and where are they installed (I'm using ubuntu 9.10) ?
Here you can find the installed Vala bindings:
ls /usr/share/vala/vapi/ (or /usr/local/share/vala/vapi/ if you have
installed from source)
In order to use a library you must have the library and its development files
installed.
On Ubuntu, for example:
'libgtk-2.0-0' and 'libgtk-2.0-dev'
'libclutter-2.0-0' and 'libclutter-2.0-dev'
...
> 2) I have never developed applications with programming languages that
> use pointers !! so in Vala where to start to understand pointers and to keep
> my applications safe from memory leaks ?
Use pointer syntax (*, ->, delete) if you want to do manual memory management.
Instead of
Foo foo = new Foo ();
foo.method ();
// object freed automatically
you can alternatively do:
Foo* foo = new Foo (); // allocate object
foo->method (); // access member
delete foo; // free object
Use it only if you really want to have full control.
> 3) Using pointers in Vala is it a must ?
No, it's best to avoid them. ('void*' can be an exception. For example, a thread
function is expected to have a 'void*' return value, which basically means
anything
can be returned. However, I'd just return 'null'.)
> 4) Where should I start to know more about using binding libraries ?
Using bindings is easy: just pass '--pkg xyz-1.0' to the compiler.
If you want to create your own bindings there are two options:
* if it's a GObject based library then you can semi-automatically generate the
bindings: http://live.gnome.org/Vala/Bindings
* otherwise you must write the '.vapi' file by hand.
http://mike.trausch.us/blog/2009/02/18/vala-bindings-for-non-gobject-type-c-libraries/
> 5) What version of unicode does Vala support ?
Strings are UTF-8 encoded.
> 6) owned, unowned, and weak modifiers I do not know how can I use them &
> why ?
The "Memory Management" section of the "Vala for C# Programmers" tutorial
explains
some of it:
http://live.gnome.org/Vala/QuickIntroForCSharpProgrammers#head-0d70172d9170f2aad9365e747aceaae818c99697
By the way, I'm working on a similar Vala quick start tutorial for Java
programmers
and will put it online within the next days.
> finally , I have developed a simple snippet to demonstrate how to use Google
> AJAX API in Vala but I did not use any thread in my code so I'm forced to use
> "--thread" to run my code perfectly I do not know why ?
I guess libsoup depends on threading support.
> Best regards,
>
> Emad Al-Bloushi
Best regards,
Frederik
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