Stian Søiland wrote:
> On 2005-07-06 16:33:47, Ron Adam wrote:
>
>
>>*No more NamesError exceptions!
>> print value
>> >> None
>
>
> So you could do lot's of funny things like:
>
> def my_fun(extra_args=None):
> if not extraargs:
> print "Behave normally"
> extra_args = 1337
>
> if extraargs:
> asdkjaskdj
> ..
> if extra_args:
> kajsdkasjd
Yes, returning None from an undefined name is DOA.
In the above case you would get an error by the way.
"if extraargs:" would evaluate to "if None:", which would evaluate to
"if:" which would give you an error.
>>*No initialization needed for a while loop!
>>
>> while not something:
>> if <condition>:
>> something = True
>
>
> This is the only "good" case I could find, but opening for a lots of
> errors when you get used to that kind of coding:
It would need to be.. while not (something==None): and the compiler
would need to handle it as a special case. But this one could still
work without allowing something=undefined to be valid.
> while not finished:
> foo()
> finished = calculate_something()
>
> (..)
> (..) # Added another loop
> while not finished:
> bar()
> finished = other_calculation()
>
> Guess the amount of fun trying to find out the different errors that
> could occur when bar() does not run as it should because the previous
> "finished" variable changes the logic.
It's not really differnt than any other value test we currently use.
notfinished = True
while notfinished:
notfinished = (condition)
# Need to set notfinished back to True here.
while notfinished:
<morestuff>
>>*Test if name exists without using a try-except!
>> if something == None:
>> something = value
>
> Now this is a question from newcomers on #python each day.. "How do I
> check if a variable is set?".
>
> Why do you want to check if a variable is set at all? If you have so
> many places the variable could or could not be set, your program design
> is basically flawed and must be refactored.
There's a few places the Python library that do exactly that.
try:
value
except:
value = something
I admit it's something that should be avoided if possible because if
there's doubt that a name exists, then there would also be doubt
concerning where it came from and weather or not it's value/object is valid.
Anyway, it was an interesting but flawed idea, I should of thought more
about it before posting it.
Cheers,
Ron
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