Hi,
On 11/11/2009 12:30 PM, r wrote:
[...snip...]
I think what has escaped everyone (including myself until my second
post) is the fact that what really needs to happen is for variable
*assignments* to return a boolean to any "statements" that evaluate
the assignment -- like in an "if" or "elif" construct. The current
"with" statement cannot replace that action and was never meant for
such things.
True. It escaped me too that the assignment was happening and I was only relying
on the side-effect to break out of the with statement. So, I'm sorry.
Very clean, very elegant solution to a messy problem that pops up in
python code quite often. It not only saves one distracting line of
code per usage but makes the code more readable. If there is an
existing solution, Steve's is not it.
However, if it is /only/ about saving that one 'distracting' line of the final
code that you are concerned about (which I think is the case), how about:
-----------------------------------------------------
def deco(f):
def assign(x):
if x:
globals()['value'] = f(x)
return True
else:
globals()['value'] = False
return assign
@deco
def something_that_returns_value(x):
# do something with x and return a value
return x
if something_that_returns_value(1) and value:
print value
if something_that_returns_value(0) and value:
print value
# or if you cannot decorate something_that_returns_value in it's definition
# for instance, a method from another module, then ...
if deco(something_that_returns_value)(0) and value:
print value
# Note that we've just siphoned off the assignment elsewhere. One problem
# tho' is, irrespective of the conditional code being entered 'value' would
# be initialized, which is what your ...
#
# if something_that_returns_value(x) as value:
#
# ... would also have done (if such a thing existed).
# To avoid this side effect we could also do:
if (something_that_returns_value(0) and value) or globals().pop('value'):
print value
# ...but that is beginning to look too much like the perl.
Well, that's all i could think of to overcome one line of extra code.
cheers,
- steve
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