Bod Soutar wrote:
> Hi,
>
> I am having some difficulty calling a class method from a different class.
> When I run the attached script like this "python cheatsheet.py --list"
>
> C:\>python cheatsheet.py --list
> done
> here?
> Traceback (most recent call last):
> File "cheatsheet.py", line 167, in <module>
> main()
> File "cheatsheet.py", line 165, in main
> ca.parseArgs()
> File "cheatsheet.py", line 39, in parseArgs
> self.argList()
> File "cheatsheet.py", line 96, in argList
> handle = cf.load()
> NameError: global name 'cf' is not defined
>
>
> So the traceback points to the issue being on line 96, specifically the
> call to cf.load(). cf.load() (line 147) is part of the cheatFile class
> (line 125), and is instantiated with cf = cheatFile() (line 161)
>
> I confess I don't know anything about classes really so I'm probably doing
> something stupid, but can anyone point me in the right direction?
>
> Thanks,
> Bodsda
Your problem has nothing to do with classes, you are trying to use a
variable outsite its scope. For example the same error will be triggered by
def print_message():
print(message)
def main():
message = "hello"
print_message()
main()
The tempting newbie fix is to make message a global variable
def main():
global message
message = "hello"
print_message()
but this makes for brittle code and you and up with lots of implicit
dependencies. Instead you should pass an argument explicitly:
def print_message(message):
print(message)
def main():
message = "hello"
print_message(message)
If you are dealing with a class you can either pass the argument to the
relevant method, or, if you need it in a lot of places make it an attribute
class Message:
def __init__(self, message):
self.message = message
def print_it(self):
print(self.message)
def main():
m = Message("hello")
m.print_it()
Can you apply that idea to your code? Your main() function will become
something like
def main():
cf = cheatFile()
print "done"
ca = cliArgs(cf)
ca.parseArgs()
Come back here if you run into problems.
By the way, Python's standard library offers an excellent way to deal with
commandline arguments, see
http://docs.python.org/library/argparse.html
which you should prefer over you self-made cliArgs.
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