How can I make a method takes the value(s) from another method from within the same class in Python

Question

I have the following Class and the corresponding method.

#!/usr/bin/env python
class Foo:
    def __init__(self, x):
        self.x = x
    def bar(self):
        bar_out = self.x + 5
        return bar_out
    def qux(self):
        qux_out = bar_out + 3
        return qux_out

def main():
    """docstring for main"""
    f = Foo(5)

    main_bar_out = f.bar()
    print main_bar_out

    #main_qux_out = f.qux()
    #print main_qux_out



if __name__ == '__main__':
    main()

What I want to do here is to make the method a=qux takes the value from bar , process it and return a value. So that the final output of main_qux_out is 13. How can I do this correctly?

Note that here I want qux() to take the value automatically from bar() , without passing any parameter.

Update

Thanks for @thefourtheye, for the response. I have further questions.

Let say if I want to have bar() to return two or more values (this can be string, string, list or dict), how can I call it from qux() . I tried this but failed.

#!/usr/bin/env python
class Foo:
    def __init__(self, x):
        self.x = x
    def bar(self):
        self.bar1_out = self.x + 5
        self.bar2_out = self.x + 1
        return (self.bar1_out,self.bar2_out)
    def qux(self):
        self.qux_out1 = self.bar1_out() + 3
        self.qux_out2 = self.bar2_out() + 6
        return ( self.qux_out1, self.qux_out2)

def main():
    """docstring for main"""
    f = Foo(5)

    mbr_out1, mbr_out2 = f.bar()
    print mbr_out1, "\t", mbr_out2

    mqx_out1, mqx_out2 = f.qux()
    print mqx_out1, "\t", mqx_out2


if __name__ == '__main__':
    main()

This should print:

10  6
13  12

Answer 1

You cannot access a local variable defined in one function, from another function. But you can invoke the bar function and use the return value like this

def qux(self):
    return self.bar() + 3

If you want to decide which value to use ( bar or the value passed as parameter) dynamically, then you can do something like this

def qux(self, myvalue = None):
    if myvalue is not None:
        return myvalue + 3
    else:
        return self.bar() + 3

If you don't pass any value to qux , myvalue will be default take None as its value. Inside the function, we check if it is not None , then we use the value as it it, otherwise we call self.bar() and use that value.

If you are planning to return two values from bar , then you can unpack them like this

def qux(self, myvalue = None):
    first, second = myvalue or self.bar()
    return first + 3, second + 6

Here myvalue or self.bar() makes sure that we take self.bar() if myvalue is None .

Note: If you are planning to do this way, then you need pass two values for myvalue as well, like this

self.qux((1, 2))

Answer 2

methods inside of a class can only access variables of that class or variables defined inside the method. What you ought to do is either make bar a variable of the class (instead of being part of the method)

def bar(self):
    self.bar_out = self.x + 5
    return self.bar_out

or call bar() and use the output in the calculation

def qux(self):    
    qux_out = self.bar() + 3