David Bolen wrote:
So for example, an asynchronous sequence of operations might be like:
d = some_deferred_function()
d.addCallback(lambda x: next_function())
d.addCallback(lambda blah: third_function(otherargs, blah))
d.addCallback(lambda x: last_function())
which to me is more readable (in terms of seeing the sequence of
operations being performed in their proper order), then something like:
def cb_next(x):
return next_function()
def cb_third(blah, otherargs):
return third_function(otherargs, blah)
def cb_last(x):
return last_function()
d = some_deferred_function()
d.addCallback(cb_next)
d.addCallback(cb_third, otherargs)
d.addCallback(cb_next)
which has an extra layer of naming (the callback functions), and
requires more effort to follow the flow of what is really just a simple
sequence of three functions being called.
But this sequence contains an error of the same form as the "fat":
while test() != False:
...code...
The right sequence using lambda is:
d = some_deferred_function()
d.addCallback(next_function)
d.addCallback(lambda blah: third_function(otherargs, blah))
d.addCallback(last_function)
And I would write it as:
def third_function_fixed_blah(blah):
def call_third(otherargs):
return third_function(otherargs, blah)
return call_third
d = some_deferred_function()
d.addCallback(next_function)
d.addCallback(third_function_fixed_blah, otherargs)
d.addCallback(last_function)
The name gives you the chance to point out that the argument order is
tweaked. In many such cases, I use curry (ASPN recipe #52549), which
should show up in Python as "partial" in the "functional" module
according to PEP 309 <http://www.python.org/peps/pep-0309.html>
(accepted but not included). I suppose it will show up in Python 2.5.
Programming is a quest is for clear, easy-to-read code, not quick,
easy-to-write code. Choosing a name is a chance to explain what you
are doing. lambda is used too often in lieu of deciding what to write.
--Scott David Daniels
[EMAIL PROTECTED]
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