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TODO list for libgpiod
==========
This document contains the list of things I'd like to have in libgpiod before
declaring it "mostly feature-complete". If anyone wants to help, this can
serve as the starting point.
==========
* implement dbus API for controlling GPIOs
A common complaint from users about gpioset is that the state of a line is not
retained once the program exits. While this is precisely the way linux
character devices work, it's understandable that most users will want some
centralized way of controlling GPIOs - similar to how sysfs worked.
One of the possible solutions is a DBus API. We need a daemon exposing chips
and lines as dbus objects and allowing to control and inspect lines using
dbus methods and monitor them using signals.
As of writing of this document some of the work has already been done and the
skeleton of the dbus daemon written in C using GLib has already been developed
and is partially functional.
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* factor out common parts of the testing framework into a separate library
We now have the core library C API and two sets of language bindings. While
the core library has proper testing using the custom framework, the tests for
C++ and Python parts are really just a bunch of examples in a single file.
The idea is to move the parts dealing with gpio-mockup loading (kmod), dummy
device detection (udev) and kernel version checking out of gpiod-test and into
a separate library called libgpiod-test that would then be reused by whatever
mechanism each set of bindings uses for testing.
This way the parts that are orthogonal to unit testing framework but necessary
for working together with the GPIO testing kernel module would not be
duplicated.
One caveat: while C++ could use this library as is, there still would be a need
for a Python wrapper around it for Python bindings.
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* porting the unit tests of core libgpiod library to using GLib
Once libgpiod-test is ready, we can think about reusing existing testing
frameworks instead of using a custom solution.
For the core C library a good candidate would be the GLib unit testing library.
GLib already provides a significant number of functionalities we currently use
like starting sub-processes, reading files, assertions plus it also offers a
range of output formatting and report generation options.
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* use a proper unit testing framework for C++ bindings and reuse libgpiod-test
The actual framework for testing is TBD but libgpiod-test could be reused as is
from C++ code so that we can use gpio-mockup just like for the core library.
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* use the python unit testing library for python bindings and reuse
libgpiod-test
The best candidate for the testing framework is the standard unittest module
available in cpython. We'd need however to wrap libgpiod-test in a C module
for python just like we did for the bindings of the core C library.
----------
* implement a simple daemon for controlling GPIOs in C together with a client
program
This is by far the lowest priority task. Similarly as with the dbus daemon:
the goal is to provide a centralized agent controlling GPIOs with a simple
interface consisting of a command line client communicating with the server
over unix sockets.
In this case however the goal is to have as few dependencies as possible. This
is because for some small systems dbus is overkill. Since we won't be using any
standardized protocol, it will take much more effort to implement it correctly.