[Pyrex] Extension types

[Greg Ewing]

Nitin Madnani wrote:
> So I am thinking about implementing all the data structures that I  need 
> as extension types in Pyrex. Is this going to be equivalent to  writing 
> my structures in pure C and using swig to create a pyhon  module? Is one 
> better than the other? Are there any overheads?

If you make all the attributes of your extension type
C attributes and use nothing but C operations on them,
then yes, it will be equivalent.

There will be no more overhead than with SWIG, and
probably less, since your extension type will directly
provide a subclassable OO interface without the need
for Python shadow classes.

Another advantage over SWIG is that Pyrex extension
types are as type-safe as built-in Python types.
(SWIG uses some dubious techniques that make
it possible to crash a SWIG-generated module from
Python code.)

On the other side, SWIG can often be made to generate
a Python interface from existing C header files with
less work than it would take using Pyrex -- although
the resulting interface will be more C-like than
Python-like.

SWIG can also generate modules for other languages
besides Python from the same description, whereas
Pyrex is Python-only. But if you're only interested
in making a Python module, this won't matter.

-- 
Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | A citizen of NewZealandCorp, a	  |
Christchurch, New Zealand	   | wholly-owned subsidiary of USA Inc.  |
greg.ewing at canterbury.ac.nz	   +--------------------------------------+