secat/cffi-python-playground

Playground for learning and testing cffi python interface

Cffi-python-playground

Playground for learning and testing cffi python interface. In order to use cffi, install it! See this page http://cffi.readthedocs.org/ for more info.

EXAMPLES

###Example 1### Shows how to build C shared library and use it via cffi.

In order to run test1 change to directory test1.

cd test1 && make

Then you can execute the cffi_test.py from any directory e.g. from the root of this repo.

Do not forget to set the LD_LIBRARY_PATH variable to directory test1 in this repo. There is located the just compiled shared library.

LD_LIBRARY_PATH=test1 python test1/cffi_test1.py

###Example 2### Shows how to wrap simple C++ shared library with C compatible header and use it in cffi.

In order to run test2 change to directory test2.

cd test2 && make

From that directory you can run

• The C program which wraps C++ library
• The Python program which uses the C++ library with C linkage

# C program launched from test2 directory
test2$ LD_LIBRARY_PATH=. ./prog my test parameters get printed
I am C program
It works!:
./prog
my
test
parameters
get
printed

# Python program launched from test2 directory
test2$ LD_LIBRARY_PATH=. python cffi_test2.py test parameters get printed
It works!:
cffi_test2.py
test
parameters
get
printed

Example 3###

I tried to use shared library which needs another shared library. In our example libtest1.so needs libtest2.so.

I am using ffi.verify function.

To compile the library and test the example run following commands.

cd test3 && make # Compile shared library and testing C program
./prog   # Run the testing C program
./cffi_test3.py  # Run the example. 

LINKS

• http://eli.thegreenplace.net/2013/03/09/python-ffi-with-ctypes-and-cffi/
• https://groups.google.com/forum/#!msg/python-cffi/
• https://pypi.python.org/pypi/cffi
• http://cffi.readthedocs.org/

PROJECTS USING CFFI

• https://github.com/search?q-cffi+python&type-Repositories&ref-searchresults
• https://github.com/felipecruz/zmqpy # failing imports
• https://github.com/apendleton/python-lz4-cffi # todo
• https://github.com/SimonSapin/cairocffi # looks maintened enough

TIPS

• Always compile with gcc
• Name your files *.c not *.cc otherwise gcc will compile it like C++ file
• During linking your shared library put -Lpathtoyourlibdirectory -lyourlibname as last parameters to gcc.