Pyrex (programming language)

Pyrex is a programming language developed to aid in creating Python modules. Its syntax is very close to Python. The goal is to make it easy for Python programmers to write the non-Python supporting code usually required for interfacing modules in a language which is as close to Python as possible.

Python itself only provides a C API to write extension modules, which allows writing of functions and datatypes in C. These can then be accessed from Python. It is thus also possible to wrap the functions and datatypes of existing C libraries as Python objects and therefore make them available to Python.

There are tools like SWIG or Python's foreign function library ctypes which can be used for this task without requiring much additional code, but this is limited to making an external library available in Python code. If adjustments to the API are needed, glue code must again be written manually. This is where Pyrex fits in.

Pyrex allows the user to write extension modules in a Python-like language which may directly access the external C code. The similarity of Pyrex's syntax to Python's makes it easy to write Python modules, as there is no need to learn another language (such as C or C++), and there may be no need to write any glue code. All that is needed is to specify the name of C-header files, enumerations, datatypes and functions needing to be accessed in the module. Then one simply uses them as if they were Python objects. The Pyrex compiler will generate the necessary glue code automatically and compile the Pyrex code into a working Python module.