Commit 0e5c9c2b authored by Yegor Yefremov's avatar Yegor Yefremov Committed by Thomas Petazzoni
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docs/manual: add "python-package CFFI backend" section 



Signed-off-by: default avatarYegor Yefremov <yegorslists@googlemail.com>
[Thomas: formatting/redaction tweaks.]
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
parent 330b112f

docs/manual/adding-packages-python.txt

+40 −0
Original line number Diff line number Diff line
@@ -160,3 +160,43 @@ possible to customize what is done in any particular step: 
  +PYTHON_FOO_BUILD_CMDS+ variable, it will be used instead of the

  default Python one. However, using this method should be restricted

  to very specific cases. Do not use it in the general case.



[[python-package-cffi-backend]]



==== +python-package+ CFFI backend



C Foreign Function Interface for Python (CFFI) provides a convenient

and reliable way to call compiled C code from Python using interface

declarations written in C. Python packages relying on this backend can

be identified by the appearance of a +cffi+ dependency in the

+install_requires+ field of their +setup.py+ file.



Such a package should:



 * add +python-cffi+ as a runtime dependency in order to install the

compiled C library wrapper on the target. This is achieved by adding

+select BR2_PACKAGE_PYTHON_CFFI+ to the package +Config.in+.



------------------------

config BR2_PACKAGE_PYTHON_FOO

        bool "python-foo"

        select BR2_PACKAGE_PYTHON_CFFI # runtime

------------------------



 * add +host-python-cffi+ as a build-time dependency in order to

cross-compile the C wrapper. This is achieved by adding

+host-python-cffi+ to the +PYTHON_FOO_DEPENDENCIES+ variable.



------------------------

################################################################################

#

# python-foo

#

################################################################################



...



PYTHON_FOO_DEPENDENCIES = host-python-cffi



$(eval $(python-package))

------------------------