Dictlite

Dictlite is a simple, lightweight implementation of a dictionary in C. It was conceived as a way to learn how to use the Python/C API and Swig to connect C code to Python. It exists on GitHub as an example of a Python-C foreign function interface to be used for learning and experimentation. So play around with it!

The dictionary itself is implemented as a linked list of key-value pairs suitable for small mappings, e.g. named parameters.

Due to its origins as a learning experience, I am afraid this code may have some fairly naive and/or incomplete parts as well as bugs. Evaluate it carefully. I may at some point make some modifications and improvements, but that is only likely if there is interest. So fork it or ask questions.

For a more mature but much more complicated example of a Python-C interface see my work on libDAI.

License

Dictlite is free, open source software. You are permitted to copy and use it however you wish. It is released under the BSD 2-Clause License. See the file LICENSE.txt in your distribution (or on GitHub) for details.

Contents

• dictlite.h, dictlite.c: Dictlite dictionary data type implementation in C.

• main.c: Example program using dictlite.

• dictlite_module.c: Dictlite as a class for CPython. This is the way to wrap C code for CPython by hand. A good example of how to write C code extending CPython with regards to error handling, incrementing and decrementing reference counts, etc.

• dictlite_swig.i: Interface definition used by Swig to generate a dictlite wrapper for CPython.

• setup.py: Python build script for building the hand-wrapped code.

• makefile: Commands for building extension modules and deleting generated files.

Requirements

• Standard Python (CPython) 2.x with development headers (Python.h)

• Swig 2.x

• GCC

Build

$ make

Run

$ python

# By-hand module
import dictlite as dl
d1 = dl.Dictlite()
d1['a'] = 1
d1[2] = 'b'
d1['c'] = 3
len(d1)  # 3
d1[2]  # 'b'
4 in d1  # False
'a' in d1  # True

# Swig-generated module
import dictlite_swig as dls
d2 = dls.Dictlite()
len(d2)  # 0
# Other methods do not work; Swig interface incomplete

Copyright (c) 2013 Aubrey Barnard. This is free software. See LICENSE.txt for details.