[capi-sig] Constructing variable arg tuples

[Todd Lyons]

On Mon, Jun 10, 2013 at 2:09 PM, Hrvoje Niksic <hniksic at xemacs.org> wrote:
>
> If my understanding is correct, you want exim configuration to define
> which Python functions will be called by exim, without an API defined
> upfront.

Thank you for phrasing it properly, I was doing such a poor job.  That
is exactly what I am doing.

>> I had to do a little work to figure out how many arguments the
>> function is written to accept, and then double check that the call
>> from the exim ACL's is using the correct number, and only then convert
>> the variables and make the function call.
> Why would you need to do that -- can't you just call the function and
> leave it to raise an exception if called with an incorrect argument count?

 Because it segfaulted instead of raising an exception.  If you remove
lines 151-158 in python.c
(http://git.exim.org/users/tlyons/exim.git/blob/4469a42e017cb6e44646d453b86e4f987fec790f:/src/src/python.c),
then it will segfault when the function is called with the incorrect
number of args.

> This will work and is easy to implement, but it does feel a bit more
> Perlish than Pythonic.  If you want to go for a solution with a more
> native Python accent, I'd recommend passing the Python function some
> sort of context argument.  Instead of a string, this would be an object
> with some methods that retrieve the message information, such as
> headers, and others to affect the response.  This needn't be a complex
> framework -- if designed carefully, excellent functionality can be
> achieved with a very small number of methods.

Noted, thanks for the input.  That's good stuff.

...Todd
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