I have no class

Seymore4Head Seymore4Head at Hotmail.invalid
Sun Nov 23 17:49:44 CET 2014


On Sun, 23 Nov 2014 11:14:34 -0500, Dave Angel <davea at davea.name>
wrote:

>On 11/23/2014 10:54 AM, Seymore4Head wrote:
>> On Sun, 23 Nov 2014 10:16:28 -0500, Dave Angel <davea at davea.name>
>> wrote:
>>
>>> On 11/23/2014 05:52 AM, Seymore4Head wrote:
>>>> On Sun, 23 Nov 2014 17:00:08 +1100, Chris Angelico <rosuav at gmail.com>
>>>> wrote:
>>>>
>>>>>
>>>>> 1) Python's namespacing rules mean that 'key' is a part of the RPS
>>>>> class, and can be referred to as 'self.key' or as 'RPS.key'
>>>>> 2) Use of 'self.key' for the textual form of the throw is shadowing
>>>>> the first of those reference names (but it's a poor name anyway)
>>>>> 3) A list would work just as well as a dictionary here, since your
>>>>> indices are sequential and start from zero
>>>>> 4) There's another function in the random module which can do both of
>>>>> your steps at once.
>>>>>
>>>>> Thank you for helping us help you help us all!
>>>>>
>>>>> ChrisA
>>>>
>>>> I wish I could explain my problems so precisely.  I will try to do
>>>> better in the future.
>>>> Thanks
>>>>
>>>> I will also try this using a list instead of a dictionary.
>>>>
>>>
>>> And please avoid the shadowing.  It's confusing whenever the same name
>>> is used for a class attribute and an instance attribute of the same
>>> class.  it can be useful for defaults and such, but not here.
>>>
>>>   class RPS:
>>>       KEY_TABLE={0:"rock", 1:"paper",2:"scissors"};
>>>    or
>>>       KEY_TABLE= ("rock", "paper", "scissors")
>>>       def __init__(self):
>>>           self.throw=random.randrange(3)
>>>           self.key=RPS.KEY_TABLE[self.throw]
>>>
>>> Note I also capitalized the tuple name, which is a convention saying we
>>> don't intend to modify it.
>>
>> I just learned by trial and error if I moved "key" out of the class, I
>> could still use it in the class without having to give it a RPS
>> extension.
>
>It's not an extension, it's a namespace qualifier.  That's a good thing, 
>to constrain a particular name to as narrow a scope as possible.  In 
>other words, instead of making it a global variable, put it in the 
>namespace that gives it meaning.
>
>>
>> I also changed it to a list and it works fine.
>>
>> Thanks
>>
>> key =["rock", "paper", "scissors"]
>> class RPS:
>>      def __init__(self):
>>          self.throw=random.randrange(3)
>>          self.key=key[self.throw]
>>
>
>But it belongs in the class, doesn't it?  If other code wants to use it, 
>it'd be better if all references were of the form  RPS.KEY_TABLE.  And 
>it should be a tuple, not a list, as you're not planning to change it.

Like I have said, most of the stuff I am doing is still trial and
error.  Having to specify RPS to use it inside the class seemed wrong
to me.

I haven't read enough about classes yet to know what the correct way
is yet.

I will leave it in.

Thanks



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