On May 16, 2006, at 6:20 PM, Simon Burge wrote:

> ]The "packed" was added back in '99 with the commit message:
>
>  Add the `packed' attribute to structures which describe wire  
> protocol data.

The idea is that it also is supposed to disable things like mandatory  
8-byte structure alignment in some ABIs.

That said, it's not clear to me that adding __packed__ to all those  
structures was the best idea in the world, because it can (and often  
does) make the code to access them much less efficient.

-- thorpej