Constructors in Python

Question

I need help in writing code for a Python constructor method.

This constructor method would take the following three parameters:

x, y, angle 

What is an example of this?

Solution 1

class MyClass(object):
  def __init__(self, x, y, angle):
    self.x = x
    self.y = y
    self.angle = angle

The constructor is always written as a function called __init__(). It must always take as its first argument a reference to the instance being constructed. This is typically called self. The rest of the arguments are up to the programmer.

The object on the first line is the superclass, i.e. this says that MyClass is a subclass of object. This is normal for Python class definitions.

You access fields (members) of the instance using the self. syntax.

Solution 2

Constructors are declared with __init__(self, other parameters), so in this case:

def __init__(self, x, y, angle):
    self.x = x
    self.y = y
    self.angle = angle

You can read more about this here: Class definition in python

Solution 3

See the Python tutorial.

Comments

[hugh]

thanks if possible can someone explain it so i can understand it and learn it

[John La Rooy]

Often a constructor may have extra parameters that should not be passed on to the parent(s) constructor

[Max Wallace]

Technically __init__ is not the constructor, __new__ is; see stackoverflow.com/questions/6130644/… The object already exists when __init__ is called, which initializes its fields.

[Nathan Basanese]

// , @giolekva Would you be willing to improve this'n?