On 19/01/17 08:31, Mark Dickinson wrote:
On Thu, Jan 19, 2017 at 1:27 AM, Steven D'Aprano <steve@pearwood.info> wrote:
[...] struct already supports variable-width formats.
Unfortunately, that's not really true: the Pascal strings it supports are in some sense variable length, but are stored in a fixed-width field. The internals of the struct module rely on each field starting at a fixed offset, computable directly from the format string. I don't think variable-length fields would be a good fit for the current design of the struct module.
For the OPs use-case, I'd suggest a library that sits on top of the struct module, rather than an expansion to the struct module itself.
Unfortunately as the OP explained, this makes the struct module a poor fit for protocol decoding, even as a base layer for something. It's one of the things I use python for quite frequently, and I always end up rolling my own and discarding struct entirely. -- Rhodri James *-* Kynesim Ltd