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= Development with EFL and tips & tricks =

== Introduction to EFL ==

The first thing that you need to know is what is '''EFL''' (or '''Enlightenment Foundation Libraries''')
 * [http://wiki.enlightenment.org/index.php/Category:Enlightenment_Foundation_Libraries A brief description] about all the EFL elements
 * [http://homepages.pathfinder.gr/kazanaki/contrib/ Introduction to EFL]: A small introduction/guide to EFL essential to understand how EFL works, include examples of the theory of work
 * [http://wiki.enlightenment.org There you can found] a lot of Howto's and documentation about the EFL's, you can write some too
 * [http://wiki.enlightenment.org/index.php/Edje Edje Concepts]


== Learning EFL ==

The best way to learn the EFL API is [http://svn.enlightenment.org/ downloading the full SVN] repository of EFL and e17 (and other things), so that there you can have a lot of examples of codes, like the directory '''TEST''' that has some [http://trac.enlightenment.org/e/browser/trunk/TEST/orig/ecore/examples examples of ecore], you can also search for ''test'' or ''example'' files/directories in the SVN

In Elive you can install the package '''efl-doc''' that includes ''updated'' (to the same version as the package efl-all that you have installed) documentation about the EFL libs, you can view the contents of the installed package using '''dpkg -L packagename''', it includes also a lot of very nice '''man'''ual pages

You can use the '''apishow''' tool (apt-get install apishow) like a FAST reference, it searches keywords in the headers of EFL

To learn basics of EFL you can read the previous link of ''introduction to EFL''


== E17 Modules ==

E17 modules could be considered like gadgets for E17, but basically they can do anything

They are more exactly C applications managed and controled by E17, using E17 features and also any thing that you would like that they can do, a '''bad''' point of this is that if ''your'' E17 module segfaults, the entire E17 segfaults too, so please write stable code on it

In the E17 SVN you can found a module called '''skel''', it is not really a module to use but more exactly a BASE of e17 module, so just copy it and start modifying the source code, you have then the basics for build your own module

But if you want something more complete you can try [http://repository.elive-systems.com/pool/main/e/emodule-creator/ the package] '''emodule-creator''' (apt-get install emodule-creator), it contain a kind of templates of e17 modules, so select your example number and you have a ready-to-compile-and-use e17 module that you can hack at what you want to make. The idea of to create in a fast way e17 modules with a pre-made code, and also to demonstrate the capabilities of e17 modules (with examples of different's things possible with e17 modules)

This is a nice youtube video demo of how to make an e17 module in 10 minutes: http://www.youtube.com/watch?v=abNsVyYTSkU

=== Some Tips & Tricks ===

From here, we suppose that you are using emodule-creator, so:
 * '''[Basic]''': You should do everything from user, of course. To compile and install a module that you have selected with emodule-creator, just enter in the directory and run '''sh autogen.sh && make && make install'''
 * If you modify the code and you want to recompile/install it, run just '''make && make install && echo -e "\nCompilation Successfully"''', after that, just restart E17 (Ctrl + Alt + END) to reload it
 * Remember that if your module crashes, all your E17 crashes, to not have this risk, use a different user and a new E17 instance in YOUR actual running E17, following these steps:
   * Create a new user from elpanel
   * Open a terminal with your user and give permissions in your graphical system for everybody can access to it, so run '''xhost +'''
   * On this terminal, change to your new user, if your new user is called ''user2'' do: '''su user2''' and go to his home directory running '''cd'''
   * You can now do everything from this user, run from it ''emodule-creator'' and start working with it
   * Now you will want to try this module from this user, in the directory '''e/trunk/e/''' of your downloaded SVN you will found a file called '''xnest.sh''' (xnest) and '''x-ui.sh''' (xephyr), copy it to the directory /usr/bin and if you run it without parameters you can see a lot of options for debugging code, just run '''xnest.sh -e''' for now, this will open a new E17 session from this user, where you can try your modules and also crash this e17 without risk for your ''real'' E17 desktop
     * '''Note''': It is recommended to use Xephyr, looks more stable and better working, do '''apt-get install xserver-xephyr''' to have it, also edit the '''x-ui.sh''' file and modify it a bit (remove the profile part, so that you will use the simple profile... so, just keep ''enlightenment_start'' without anything more than this), also change your resolution/colors to something like 800x600 (no colors parameter needed)
 * When you install a module, they are located in '''.e/e/modules''' directory of the home of the user, but if you want to remove it its recommended to just do '''make uninstall''' in the source code of the module
 * Since you disable and unload a module in your e17 dir, you should have not any risk from this module if can segfault
 * If your E17 system be totally unusable because a module that made him segfaulting just starting, you may be remove entirely your '''.e''' directory of the user's home, but in elive is recommended to run instead the command '''elive-skel upgrade .e''' from that user
 * If you have any thing that doesn't change from your modifications, try to run '''make clean''' before to recompile it
 * When you use the template '''05''' of emodule-creator, there's something in the source code that mades the middle-click of the mouse to restart e17, using this feature, when you run the command for ''recompile and install'', before to try it you need to exit from E17 and enter again, a faster solution is just to restart it, and a good way to do this in a fast way is just clicking in the module (middle-click) that you are working on :)


== Misc ==

 * [http://wiki.enlightenment.org/index.php/Autotools_Integration Autotools]: A very nice howto about how to create your Makefiles (& co) architecture files in the better way and without the help of external bloated editors that creates them by yourself
 * '''EDJE''': If you want to do an [http://wiki.enlightenment.org/index.php/Edje Edje] interface, after to learn how (with the previous listed links) you can use a [http://cored.org/edje/documentation/edje_reference.png fast reference card] or [http://docs.enlightenment.org/api/edje/html/edcref.html a more complete reference] (with explanations of elements)


== Notes == 

In Elive you have a good environment ''ready to use'' to develop with EFL:
 * It is '''strongly''' recommended to use the last version of Elive and/or the last available version of EFL packages (the next command should upgrade it: ''apt-get update && apt-get install efl-all'' ), you will also require to install some dependencies that you maybe can't have installed yet, in any case to be sure you can just install the package '''emodule-creator''' because it installs also the required dependencies to build (at least) e17 modules
 * '''Vim''': If you like to edit with Vim, you can like the configurations included by default in Elive for vim and EFL, apart to have a nice configuration by deafult, it includes syntax hilighting for '''EDC''' files, it also has by default the best (IMHO) colour theme for any language, specially '''C''' and '''Bash''', this should be the better colors theme for a fast reading of the code and to found parts in the code fast, [http://main.elivecd.org/images/shots/vim-colors.png there's an Screenshot]