Book Image

Learning Cython Programming (Second Edition) - Second Edition

By : Philip Herron
Book Image

Learning Cython Programming (Second Edition) - Second Edition

By: Philip Herron

Overview of this book

Cython is a hybrid programming language used to write C extensions for Python language. Combining the practicality of Python and speed and ease of the C language it’s an exciting language worth learning if you want to build fast applications with ease. This new edition of Learning Cython Programming shows you how to get started, taking you through the fundamentals so you can begin to experience its unique powers. You’ll find out how to get set up, before exploring the relationship between Python and Cython. You’ll also look at debugging Cython, before moving on to C++ constructs, Caveat on C++ usage, Python threading and GIL in Cython. Finally, you’ll learn object initialization and compile time, and gain a deeper insight into Python 3, which will help you not only become a confident Cython developer, but a much more fluent Python developer too.
Table of Contents (14 chapters)
Learning Cython Programming Second Edition
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Preface
Index

Cython keyword – cdef


The cdef keyword tells the compiler that this statement is a native C type or native function. Remember from Chapter 1, Cython Won't Bite that we used this line to declare the C prototype function:

cdef int AddFunction(int, int)

This is the line that let us wrap the native C function into a Python callable using the Python def keyword. We can use this in many contexts, for example, we can declare normal variables for use within a function to speed up execution:

def square(int x):
    return x ** 2

This is a trivial example, but it will tell the compiler that we will always be squaring an integer. However, for normal Python code, it's a little more complicated as Python has to worry a lot more about losing precision when it comes to handling many different types. But in this case, we know exactly what the type is and how it can be handled.

You might also have noticed that this is a simple def function, but because it will be fed to the Cython compiler, this will work just...