Ron wrote:
> It's interesting that there is a whole is_"type"_() group of functions
> in the inspect module, but not a is_defined(). Maybe I just haven't
> found it yet.
I've never found any need for an is_defined function. If in doubt I just
make sure and initialise all variables to a suitable value before use.
However, I'll assume you have a good use case.
>
>
> #############
>
> def if_not_defined(v, dv=None, lv=locals()):
> if lv.has_key(v):
> return lv[v]
> return dv
I don't see the point of the default argument. locals() at the global level
simply returns globals, so you might as well use that. A more useful
default would be the caller's locals.
>
> def is_defined(v, lv=locals()):
> if lv.has_key(v):
> return True
> False
Same comments, plus the whole 'if on a boolean to return a boolean' is a
bit redundant.
Try something on these lines:
>>> import inspect
>>> def is_defined(name, lv=None):
if lv is None:
lv = inspect.currentframe().f_back.f_locals
return name in lv
>>> is_defined('abc')
False
>>> abc = 3
>>> is_defined('abc')
True
>>> def f(x):
print is_defined('x')
print is_defined('y')
y = 0
print is_defined('y')
>>> f(2)
True
False
True
>
> # Shorten names and pass locals() with lambas for
> # convenience. (This needs to be in the function
> # where they are used or it will break.
> # Another use for lamba! ;)
>
> ifnd = lambda v, dv, lv=locals(): if_not_defined(v,dv,lv)
> isa = lambda v, lv=locals(): is_defined(v, lv)
There is no need for lambda here, it adds nothing. Use a 'def'.
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