development.txt

#
# Copyright © 2011-2017 Andreas Rönnquist.
# This file is distributed under the same license
# as the devilspie2 package, see COPYING file.
#

Devilspie2 development
======================

Git is used for version control for devilpsie2. If you would like to provide
code to devilspie2, the first thing to do is - learn git.

Number two to think about is if you are willing to release your code as
GPL. Devilspie2 is released under the GPL license version 3, and I will
only accept code under that license.

As with any C program, program execution starts in the main function - which
is placed in devilspie2.c in this case. The main function interprets the
command line options, sets up a list of script files that should be
interpreted, and registers the signal for window_opened to the proper callback
function.


Adding a new script function
============================

Add it in script.c in the function "register_cfunctions", using a
lua_register call - To add a function having the lua name "center", and connect
it with the C function c_center, do this:

lua_register(lua,"center", c_center);

This registers a center function, that will call the c_center function in the
C code. The C function should be placed in script_functions.c & its header,
with the following prototype:

int c_center(lua_State *lua);

What is returned is an integer represeting the amount of return values that the
Lua function returns. These return values are pushed to the stack using a
lua_push for the correct type - for example lua_pushboolean(lua, TRUE);

And logically if there are nothing to return, we simply do a "return 0;".

If we need something that isn't directly implemented in libwnck, we can add
a function implementing it to the file "xutils.c" - please separate stuff from
script_functions if it has no need to be there, and simply call it from your
function in script_functions.c. The point is to keep input and Lua interpreting
to script_functions, while the actual wnck and/or X work is in the xutils files.