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Anthony Grodowski
4,902 PointsProblem with name
I can't quite get why we need to set name keyword argument in order to run the code. Why do we put name="" in the init? TIA
1 Answer
Chris Freeman
Treehouse Moderator 68,457 PointsGood question. Keep in mind that a supplied positional argument would be applied to the first available parameter, be it positional or keyword parameter!
With the inclusion of Agile and Sneaky, the first positional argument "Kenneth" would be applied to the agile parameter:
# Note: `name=foo` added to pass `if not name:` test
>>> thieves.Thief("Kenneth", sneaky=True, name="foo").__dict__
{'name': 'foo', 'sneaky': True, 'agile': 'Kenneth'}
The attribute agile gets assigned "Kenneth"!
Why do we put name="" in the __init__? By supplying a default value for the parameter name it covers the case where the name might have been swallowed up by a previous positional assignment. If all the parameters are provided, keyword use isn't necessary. But if one parameter isn't filled, then name would become the default empty string and the check in Character would raise the error.
>>> thieves.Thief(True, True, "Kenneth").__dict__
{'name': 'Kenneth', 'sneaky': True, 'agile': True}
>>> thieves.Thief(True, "Kenneth").__dict__
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/chris/devel/Treehouse/Thief/attributes.py", line 19, in __init__
super().__init__(*args, **kwargs)
File "/home/chris/devel/Treehouse/Thief/attributes.py", line 8, in __init__
super().__init__(*args, **kwargs)
File "/home/chris/devel/Treehouse/Thief/characters.py", line 4, in __init__
raise ValueError("'name' is required")
ValueError: 'name' is required
Post back if you need more help. Good luck!!
Anthony Grodowski
4,902 PointsAnthony Grodowski
4,902 PointsThnak you! That cleared almost everything!
"With the inclusion of Agile and Sneaky, the first positional argument "Kenneth" would be applied to the agile parameter" - but if in
Agilethere would be, for example,agile = "Able To Dodge", then "Kenneth" parameter couldn't overwrite it, right?True,FalseandNonecould be eaisly overwritten by "Kenneth", but explicit keyword argument can't.Chris Freeman
Treehouse Moderator 68,457 PointsChris Freeman
Treehouse Moderator 68,457 PointsAgain, good question!
Important point: a function only has parameters, some may have default values define, others may not.
Having a default value for a parameter does not protect it being assigned to a positional argument.
In my answer above,
agileis assigned “Kenneth” even though it has a default valueTrueKeywords only come into play if the argument in the statement calling the function has a keyword with the argument. In this case the argument will only be applied to the parameter of the same name.
If “Kenneth” had been used as an argument along with
agile=Truethen an error would be raised sayingError: agilealready assign an argument`