[Twisted-Python] Re: question about deferred lists tutorial description

[Terry Jones]

Hi Josef

> Apologies for the previous premature email; it seems I cannot read. 

:-)

> The apparent contradiction I mentioned was the result of my conflating
> 'callback' with 'addCallback'.

Right.

> However, I guess I'd still appreciate some discussion on the nuances of
> these two functions.

It's just a trivial non-real-world example. The use of callback is to
supply a return value, which is passed to the function added with
addCallback (and similarly with errback).  In a non-trivial example, some
other code (associated with the function that returned the deferred) would
be what called callback (or errback). The example just shows all the code
in one place.  Does that make sense?

Terry