Cython Wrapping

A collection of examples to wrap C++-Code using Cython to be able to use it within Python.

Prerequisites

1. Create a virtual Python environment (e.g. using conda)
   conda create -n wrapper Python=3.7
   

2. Inside the created environment install the required packages
   conda activate wrapper
conda install -c anaconda pip
pip install -r requirements.txt
   

3. Go to one of the subdirectories (e.g. 01_simple_c_wrapper) and follow the steps there (stay in the wrapper virtual environment).
   

The code has been tested on MacOS (10.9) and Linux (Ubuntu 18.04 LTS).

01 Simple C Wrapper

Wrapping a function in C that takes a string and prints that string on the console.

References:

• Wrapping C libraries with Cython
• Convert str to bytes

02 Simple C++ Wrapper

Wrapping a function in C++ that takes a string and prints that string on the console.

References:

• Wrapping C libraries with Cython
• Convert str to bytes
• How do I check the operating system in Python?
• sys.platform
• GCC -fPIC option
• cc1plus: warning: command line option “-Wstrict-prototypes” is valid for Ada/C/ObjC but not for C++

03 C++ Array Wrapper

Wrapping a function in C++ that takes an array and a number and multiplies that number to each element of the array.

References:

• MemoryViews in Cython
• Numpy in Cython
• How do I check the operating system in Python?
• sys.platform
• GCC -fPIC option
• cc1plus: warning: command line option “-Wstrict-prototypes” is valid for Ada/C/ObjC but not for C++
• Best way to convert numpy array to C++ vector?
• How to initialize std::vector from C-style array?
• Getting Started With Testing in Python
• Best way to assert for numpy.array equality?
• Python test to check instance type
• Using nose2

04 C++ Class Wrapper

Wrapping a class in C++ that encapsulates an array and provides various functions to handle that array (sum of its elements, getting array length, getting array itself, multiplying each element by a constant).

References:

• From C++ to Numpy
• From C++ to Numpy (old?)
• MemoryViews in Cython
• C++ in Cython
• How do I check the operating system in Python?
• sys.platform
• GCC -fPIC option
• cc1plus: warning: command line option “-Wstrict-prototypes” is valid for Ada/C/ObjC but not for C++
• Getting Started With Testing in Python
• Best way to assert for numpy.array equality?
• Python test to check instance type
• Using nose2

05 C++ MultiClass Wrapper

Wrapping multiple class in C++. Again, we have one class that encapsulates an array. Furthermore, we have another class that takes a constant as input and offers a function which takes a vector class and multiplies each element of the vector class by the constant.

References:

• C++ in Cython
• Nullary Constructor
• How do I check the operating system in Python?
• sys.platform
• GCC -fPIC option
• cc1plus: warning: command line option “-Wstrict-prototypes” is valid for Ada/C/ObjC but not for C++
• Getting Started With Testing in Python
• Best way to assert for numpy.array equality?
• Python test to check instance type
• Using nose2

06 C++ Dependency Wrapper

Wrapping a class in C++ that encapsulates an array and provides various functions to handle that array (sum of its elements, getting array length, getting array itself, multiplying the array with another array). Internally the C++ class uses OpenCV as external library.

References:

• From C++ to Numpy
• From C++ to Numpy (old?)
• MemoryViews in Cython
• C++ in Cython
• How do I check the operating system in Python?
• sys.platform
• GCC -fPIC option
• cc1plus: warning: command line option “-Wstrict-prototypes” is valid for Ada/C/ObjC but not for C++
• Getting Started With Testing in Python
• Best way to assert for numpy.array equality?
• Python test to check instance type
• Using nose2
• How to convert C++ array to opencv Mat
• dot product
• Wrap a c++ class that uses Armadillo by Cython

07 Wrapper Package

Creating a package called pymath containing a regular Python class and a Cython class that wraps a C++ class. The package can be installed using pip.

References:

• Packaging Python Projects
• Creating a Python package
• Choose an open source license
• Classifiers
• How do I install a Python package with a .whl file?
• Install dependencies from setup.py
• install_requires vs requirements files
• How do I check the operating system in Python?
• sys.platform
• GCC -fPIC option
• cc1plus: warning: command line option “-Wstrict-prototypes” is valid for Ada/C/ObjC but not for C++
• OS detecting makefile
• Getting Started With Testing in Python
• Best way to assert for numpy.array equality?
• Python test to check instance type
• Using nose2
• What is the correct way to share package version with setup.py and the package?
• 5 common patterns to version your Python package
• Distributing Cython modules
• How should I structure a Python package that contains Cython code
• Wrapping a DLL: C++ to Cython to Python