mutter/HACKING
Emmanuele Bassi c418b23baf [docs] Add a bindings coding practices
When writing language bindings for Clutter some rules should be
observed to guarantee the same levels of quality across different
bindings.
2009-03-12 09:29:39 +00:00

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GENERAL
=======
General notes and rules on clutter core hacking;
- Follow the CODING_STYLE document.
- Really, follow the CODING_STYLE document.
- All non static public API funcs should be documented in the source files
via gtk-doc. Structures, enumerations and macros should be documented in
the header files.
- All non-trivial static and private API should be documented, especially
the eventual lifetime handling of the arguments/return values or locking
of mutexes.
- All public functions with floating point arguments should also provide a
fixed point version, with the 'x' postfix to the function name, e.g.:
clutter_actor_set_foo - floating point
clutter_actor_set_foox - fixed point
Fixed point might also be used internally if the 16.16 precision and
range allow it.
- All public functions dealing with pixels should also provide a
ClutterUnit version, with the 'u' postfix to the function name, e.g:
clutter_actor_set_bar - pixels
clutter_actor_set_baru - units
ClutterUnit should always be used internally.
- Properties should always be in floating point (never fixed point).
The preferred precision is double for angles, and single precision
for size and position -- especially if they have to be passed down
to COGL.
- Properties should use pixels whenever is possible. If sub-pixel
precision is fundamental, use ClutterParamSpecUnit and
clutter_param_spec_unit() to install ClutterUnit properties, and
clutter_value_set_unit()/clutter_value_get_unit() to handle GValues in
a safe way. Never install a ClutterUnit property using a GParamSpecInt,
GParamSpecFloat or GParamSpecDouble.
- Public entry points must always check their arguments with
g_return_if_fail() or g_return_val_if_fail().
- Private entry points should use g_assert() to verify internal state;
do not use g_return_if_fail()/g_return_val_if_fail() as they might
be compiled out.
- If you need to share some state variable across source files use
ClutterContext and a private accessor.
- Private, non-static functions must begin with an underscore and
be declared inside clutter-private.h.
- Don't add direct GL calls but add API to COGL (both GL and GL|ES
versions if possible).
- Use the CLUTTER_NOTE() macro for debug statements in Clutter, and
the COGL_NOTE() macro for debug statements in COGL. If necessary,
add a value inside ClutterDebugFlags or CoglDebugFlags to specify
the debug section.
- New features should also include an exhaustive test unit under
tests/conform and, eventually, a user-interactive test under
tests/interactive.
- When committing, use the standard git commit message format:
short description - MUST be less than 74 characters
<newline> - MANDATORY empty line
long description - Each line must be less than 80 characters
Do NOT put the commit message on the short description line.
One line commit messages should be avoided, unless they can be
*fully* explained in less than 70 characters (e.g. "Fix typo in
clutter_actor_create_pango_context() docs"). Think of the commit
message as an email sent to the maintainers explaining "what" you
did and, more importantly, "why" you did it. The "how" is not
important, since "git show" will show the patch inlined with the
commit message.
LANGUAGE BINDINGS
=================
- Language bindings should not wrap the fixed-point entry points of the
API; the functions that usually accept fixed-point values are convenience
functions for C developers.
- Similarly, ClutterUnit is a convenience type for the C library. It can
be safely wrapped as a floating point value, but it should be converted
to and from a floating point value using the provided macros.
- To reduce the amount of entry points, methods with the -u suffix can be
wrapped either by overloading (if your language allows it) or by making
every Unit-based function the only entry point, e.g. wrapping
clutter_actor_get_position() as accepting floating point values as
parameters and calling clutter_actor_get_positionu() internally after
having converted the argument types.
RELEASES
========
In making a new release;
- Check out a fresh copy from SVN.
- Verify versioning in configure.ac, increasing relevant
clutter_major_version/clutter_minor_version/clutter_micro_version
value. For point releases, bump clutter_micro_version to the next
even number.
- If there was no API change (addition, removal), increment
clutter_interface_age by two. If there was an API change,
set clutter_interface_age to zero. The interface_age is used to
keep the soname the same.
- Update NEWS (New feature details, bug #'s), README (Any API changes
relevant to developers + version), AUTHORS if relevant.
- Add a Release entry to the ChangeLog noting version.
- Call make distcheck and fix if fails.
- Upload the tarball.
- Bump clutter_micro_version to the next odd number version.
- Commit.
- Announce release to waiting world on blog and mailing list.
- Release any dependant add-ons following similar rules to above.
Dont forget to check *.pc file version deps!
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