[Alex Martelli]
> ...
> not_empty and not_full are not methods but rather instances of the
> threading.Condition class, which gets waited on and notified
> appropriately. I'm not entirely sure exactly WHAT one is supposed to do
> with the Condition instances in question (I'm sure there is some design
> intent there, because their names indicate they're public); presumably,
> like for the Lock instance named 'mutex', they can be used in subclasses
> that do particularly fiendish things... but I keep planning not to cover
> them in the 2nd edition of the Nutshell (though there I _will_ cover the
> idea of subclassing Queue to implement queueing disciplines other than
> FIFO without needing to worry about synchronization, which I had skipped
> in the 1st edition).
Last time it was rewritten, I put as much thought into the names of
Queue instance variables as Guido put into them originally: none.
They have always "looked like" public names, but I'm at a loss to
think of anythng sane a Queue client or extender could do with them.
Of course that's why the docs don't mention them. I suppose an
extender could make good use of `mutex` if they wanted to add an
entirely new method, say:
def get_and_put_nowait(self, new_item) :
"""Pop existing item, and push new item, atomically [blah blah blah]."""
I don't know of anyone who has done so, though. I kept the name
`mutex` intact during the last rewrite, but didn't hesitate to get rid
of the former `esema` and `fsema` attributes. Since no complaints
resulted, it's a pretty safe bet nobody was mucking with esema or
fsema before.
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