Building a Hello World program

As is the tradition with programming languages, we will start with a Hello World example. Unlike with Python, we need to compile Cython code. We start with a .pyx file, from which we will generate C code. This .c file can be compiled and then imported into a Python program.

How to do it...

This section describes how to build a Cython Hello World program.

1. Write the hello.pyx code.

   First, we will write some pretty trivial code that prints "Hello World". This is just normal Python code, but the file has the pyx extension.

   def say_hello():
   print "Hello World!"

2. Write a distutils setup.py script.

   We need to create a file named setup.py to help us build the Cython code.

   from distutils.core import setup
   from distutils.extension import Extension
   from Cython.Distutils import build_ext
   
   ext_modules = [Extension("hello", ["hello.pyx"])]
   
   setup(
           name = 'Hello world app',
           cmdclass = {'build_ext': build_ext},
           ext_modules = ext_modules
        )

   As you can...