[Python-Dev] PEP: Adding data-type objects to Python

[Bill Baxter]

One thing I'm curious about in the ctypes vs this PEP debate is the following. 
How do the approaches differ in practice if I'm developing a library that wants
to accept various image formats that all describe the same thing: rgb data. 
Let's say for now all I want to support is two different image formats whose
pixels are described in C structs by:

struct rbg565
{
  unsigned short r:5;
  unsigned short g:6;
  unsigned short b:5; 
};

struct rgb101210
{
  unsigned int r:10;
  unsigned int g:12;
  unsigned int b:10; 
};


Basically in my code I want to be able to take the binary data descriptor and
say "give me the 'r' field of this pixel as an integer".

Is either one (the PEP or c-types) clearly easier to use in this case?  What
would the code look like for handling both formats generically?

--bb