Python：如何从类中的函数调用特定变量？

Question

I have Basic question How do I call a specific variable from a function inside the class? let say I have this

class One():
    def fncOne():
        fileOne = "one"
        filetwo= "two"
        filethree= "three"

        return fileOne ,filetwo,filethree

fncOne() // Will call all of them together

But I want to call only one of them to print it fncOne().filetwo

Thank you,

Answer 1

The way your code is structured now, I don't think anything will happen at all. First, you made a class with a method inside of it, but the method has no "self" argument so you will get an error. Second, the "return" is not inside of the method.

Even if you fix where the return is, as soon as you instantiate the "One" object, an error will be thrown:

class One():
    def fncOne():
        fileOne = "one"
        filetwo = "two"
        filethree = "three"
        return fileOne, filetwo, filethree

a = One()
a.fncOne()

This will get you: TypeError: fncOne() takes 0 positional arguments but 1 was given

However, if you take the method out of the class definition, the above comments are fine:

def fncOne():
    fileOne = "one"
    filetwo = "two"
    filethree = "three"
    return fileOne, filetwo, filethree

fncOne()[1]

That will return 'two' as you desire.

However, you want to keep the class so maybe what you need to do instead is:

class One(object):
    def __init__(self):
        self.fileOne = "one"
        self.fileTwo = "two"
        self.fileThree = "three"

myObject = One()
myObject.fileTwo

That will return 'two' because 'fileTwo' is now an attribute of the class One.

Answer 2

fncOne returns tuple (of three elements) in your case.

You can either index like this:

one.fncOne()[1]

... or use more pythonic tuple unpacking:

(_, filetwo, _) = one.fncOne()

Note that you seem to have number of issues in your code, like missing self in method definition.