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Python Object-Oriented Python Advanced Objects Subclassing Built-ins

Posted by eodell
eodell
26,386 Points

Why doesn't Python print attributes of the JSO that were added through __getattribute__?

Hello. I am following along with Kenneth but am not fully understanding:

  1. Why, after adding the attributes 'fake' and 'language'to jso, the function 

    print(fso)

    only returns the name attribute that was added when it was created: 

    jso = JavaScriptObject({"name":"Kenneth"})

    Perhaps I've made an error in my code but I receive no errors when executing

  2. Also, I don't fully understand the purpose of:

        except KeyError:
          return super(JavaScriptObject, self).__getattribute__(item)

why would the results of getattribute(item) from the dictionary class produce different results?

Any and all insight would be greatly appreciated!

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points
  1. Why does the print only return the name?

In a print context, the return value of fso (jso?) would be the results of the __str__ method. Perhaps this method only returns the JSO name attribute.

  1. What is the purpose of the code:
    except KeyError:
          return super(JavaScriptObject, self).__getattribute__(item)

When getting a local instance attribute, a KeyError may be raised if the attribute is not found. In this situation, instead of raising the error, the code calls the parent class's __getattribute__ to access the class attributes.