Multiple constructors in python, using inheritance

Question

I have a class AbstractDataHandle, whith his init method, and a class Classifier. I would like to have two constructors in Classifier, Java like. One inheri

Answer 1

There are the methods in the accepted answer, but I think this one is fairly flexible. It's convoluted, but very flexible.

When the class is instiated, init calls a method and pass it a string argument (obtained from instantiation). That function uses conditionals to call the right "constructor" function to initialize your values, let's say you have different sets of possible starting values.

If you need to provide other arguments (e.g. that might have a value only at runtime), you can use default values in init() to allow optional arguments, and initialize those in init as you normally would.

class MyClass:
def __init__(self,argsSet1, otherAttribute="Assigning this default value 
             to make this other argument optional",):
    self.selectArgSet(argsSet1)
    self.otherAttribute = otherAttribute
    print otherAttribute
def selectArgSet(self,ArgSet1):
    if ArgSet1 == "constructorArgSet1":
        self.constructorArgSet1()
    elif ArgSet1 == "constructorArgSet2":
        self.constructorArgSet2()
def constructorArgSet1(self):
    print "Use this method as Constructor 1"
    self.variable1 = "Variable1 value in Constructor 1"
    self.variable2 = "Variable2 value in Constructor 1"
    print self.variable1
    print self.variable2
def constructorArgSet2(self):
    print "Use this method as Constructor 2"


      self.variable1 = "Variable1 value in Constructor 2"
        self.variable2 = "Variable2 value in Constructor 2"
        print self.variable1
        print self.variable2

myConstructor_1_Instance = MyClass("constructorArgSet1")
myConstructor_2_Instance = MyClass("constructorArgSet2", "You can still 
                                           initialize values normally")

The output of which is:

Use this method as Constructor 1

Variable1 value in Constructor 1

Variable2 value in Constructor 1

Assign default value to make this other argument optional

Use this method as Constructor 2

Variable1 value in Constructor 2

Variable2 value in Constructor 2

You can still initialize values normally