Re: [Spyce-users] keyword args

[Rimon B. <ba...@cs...>]

Hi James,

>I will have to overide the init method of the spyceModule class to do
>this won't I? I see the session module does this:

Exactly. The module.init method gets called at the point of the
[[.import]] directive, with any arguments and keyword argments. In fact,
if the [[.import]] looks like:
  [[.import name=foo args="1, 2, 3"]]
then you will get a call:
  foo.init(1, 2, 3)
All the Spyce compiler does is take the args string and insert it inside:
  foo.init(...).
The rest is done by Python, including the syntax checking and the
parameter at runtime!

Moving onto the specific example:

>def init(self, handler=None, *args, **kwargs):
>     if handler:
>       session = apply(self.setHandler, (handler,)+args)
>       if kwargs.has_key('auto') and kwargs['auto']:
>         auto = kwargs['auto']
>         if type(auto) != type(()):
>           auto = (auto,)
>         apply(session.autoSession, auto)
>
>Can I just follow this example? Not a 100% sure, but is this bit of
>code doing anything else other then trying to also check for a handler
>and initiate the setHandler call? I am not sure what lines 6 and 7 do
>there actually but...

Yes, and a little bit more. It's able to deal with something like the
following (taken from examples/autosession.spy):
  [[.import name=session args="'session_dir', '/tmp', auto=10"]]

The handler is session_dir. The '/tmp' parameter (but it could also be
more than one parameter) is passed to initialize session_dir handler.
And the auto parameter (or parameters, that's the tricky part), if it
exists is/are passed to the autoSession() method. Now, auto could either
be just an integer, or a tuple (sec, [method], [name]). If it's just an
integer, I wrap it up as a tuple first, before passing it on. Basically,
lots of junk that specific to the flexible syntax that I came up with for
import the session module. You don't have to worry about all that.

Just know that the args string is pasted verbatim inside a call to
module.init(...). And, if there is a syntax error, due to mismatched
parameters and such, Python will pick it up. The standard Python parameter
assignment rules apply. Hence we get the *, ** functionality for free, and
it's useful in creating flexible init methods. Note that in the case of
  [[.import name=foo]]
you WILL get a call:
  foo.init()
The default method that is inherited from spyceModule will accept any
number of arguments and does nothing. I hope that helps.

All the best,
Rimon.