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Python Object-Oriented Python Advanced Objects Controlling Conversion

Posted by daniel steinberg
daniel steinberg
14,651 Points

def __str__(self): return "{}: {}".format(self.__class__.__name__, self.name)

When I add this line to Characters nothing is printed when I run play.py. How does the teacher get "Thief: Kenneth" from just the Method Return with no print command?

I had to add this to play.py to get it to output the returned value: print(kenneth.str())

KRIS NIKOLAISEN
KRIS NIKOLAISEN
54,971 Points

Can you post a snapshot of your workspace? Click the camera icon in the upper right corner, then click 'Take Snapshot', then post the link that is created here.

1 Answer

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

In the video, there is a print command that displays "Thief: Kenneth" — it's in the play.py file: "print(kenneth)"

And the reason that it works (and you don't need "print(kenneth.__str__())") is because the system automatically invokes the __str__ method on a thing when you print it.

daniel steinberg
daniel steinberg
14,651 Points

Thanks so much. In general I love Treehouse but this section and this instructor I find hard to follow. So when you print an instance of a class, Python looks for a str method..what of there is more than one..does it print all of them.. the first one?

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

Method names must be unique, you can only have one method of any particular name in a class.

daniel steinberg
daniel steinberg
14,651 Points

TY!..can you have an str method in a class and import another class that has an str? If yes what happens then when you print?

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

Method names only need to be unique within the same class. Methods in other classes are completely separate and will not conflict.

daniel steinberg
daniel steinberg
14,651 Points

ty...if there is a strmethod in both a class and you import another class that has a_str_ method, what will happen when you use print()..how will python know which one use?

Steven Parker
Steven Parker
231,198 Points
Steven Parker
Steven Parker
231,198 Points

It only uses the method defined for that same class (the class of the thing you are printing). Methods in other classes (even if they have the same name) are completely separate.

Think of method and class like city and state. If you get on a plane going to Arlington, Virginia it doesn't land in Arlington, Texas.