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a50b8572f0
This is not strictly needed functionality-wise, but doing this allows
sphinx to see which decorated methods are async. Without this, sphinx
misses the "async" classifier on generated docs, which ... for an async
library, isn't great.
It does make an already gnarly function even gnarlier, though.
So, what's going on here?
A synchronous function (like require() before this patch) can return a
coroutine that can be awaited on, for example:
def some_func():
return asyncio.task(asyncio.sleep(5))
async def some_async_func():
await some_func()
However, this function is not considered to be an "async" function in
the eyes of the abstract syntax tree. Specifically,
some_func.__code__.co_flags will not be set with CO_COROUTINE.
The interpreter uses this flag to know if it's legal to use "await" from
within the body of the function. Since this function is just wrapping
another function, it doesn't matter much for the decorator, but sphinx
uses the stdlib inspect.iscoroutinefunction() to determine when to add
the "async" prefix in generated output. This function uses the presence
of CO_COROUTINE.
So, in order to preserve the "async" flag for docs, the require()
decorator needs to differentiate based on whether it is decorating a
sync or async function and use a different wrapping mechanism
accordingly.
Phew.
Signed-off-by: John Snow <jsnow@redhat.com>
cherry picked from commit python-qemu-qmp@40aa9699d619849f528032aa456dd061a4afa957
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
QEMU Python Tooling
===================
This directory houses Python tooling used by the QEMU project to build,
configure, and test QEMU. It is organized by namespace (``qemu``), and
then by package (e.g. ``qemu/machine``, ``qemu/qmp``, etc).
``setup.py`` is used by ``pip`` to install this tooling to the current
environment. ``setup.cfg`` provides the packaging configuration used by
``setup.py``. You will generally invoke it by doing one of the following:
1. ``pip3 install .`` will install these packages to your current
environment. If you are inside a virtual environment, they will
install there. If you are not, it will attempt to install to the
global environment, which is **not recommended**.
2. ``pip3 install --user .`` will install these packages to your user's
local python packages. If you are inside of a virtual environment,
this will fail; you want the first invocation above.
If you append the ``--editable`` or ``-e`` argument to either invocation
above, pip will install in "editable" mode. This installs the package as
a forwarder ("qemu.egg-link") that points to the source tree. In so
doing, the installed package always reflects the latest version in your
source tree.
Installing ".[devel]" instead of "." will additionally pull in required
packages for testing this package. They are not runtime requirements,
and are not needed to simply use these libraries.
Running ``make develop`` will pull in all testing dependencies and
install QEMU in editable mode to the current environment.
(It is a shortcut for ``pip3 install -e .[devel]``.)
See `Installing packages using pip and virtual environments
<https://packaging.python.org/guides/installing-using-pip-and-virtual-environments/>`_
for more information.
Using these packages without installing them
--------------------------------------------
These packages may be used without installing them first, by using one
of two tricks:
1. Set your PYTHONPATH environment variable to include this source
directory, e.g. ``~/src/qemu/python``. See
https://docs.python.org/3/using/cmdline.html#envvar-PYTHONPATH
2. Inside a Python script, use ``sys.path`` to forcibly include a search
path prior to importing the ``qemu`` namespace. See
https://docs.python.org/3/library/sys.html#sys.path
A strong downside to both approaches is that they generally interfere
with static analysis tools being able to locate and analyze the code
being imported.
Package installation also normally provides executable console scripts,
so that tools like ``qmp-shell`` are always available via $PATH. To
invoke them without installation, you can invoke e.g.:
``> PYTHONPATH=~/src/qemu/python python3 -m qemu.qmp.qmp_shell``
The mappings between console script name and python module path can be
found in ``setup.cfg``.
Files in this directory
-----------------------
- ``qemu/`` Python 'qemu' namespace package source directory.
- ``tests/`` Python package tests directory.
- ``avocado.cfg`` Configuration for the Avocado test-runner.
Used by ``make check`` et al.
- ``Makefile`` provides some common testing/installation invocations.
Try ``make help`` to see available targets.
- ``MANIFEST.in`` is read by python setuptools, it specifies additional files
that should be included by a source distribution.
- ``PACKAGE.rst`` is used as the README file that is visible on PyPI.org.
- ``README.rst`` you are here!
- ``VERSION`` contains the PEP-440 compliant version used to describe
this package; it is referenced by ``setup.cfg``.
- ``setup.cfg`` houses setuptools package configuration.
- ``setup.py`` is the setuptools installer used by pip; See above.