Constructor (object-oriented programming): Difference between revisions

Revision as of 09:17, 18 January 2016

Revision as of 06:44, 22 January 2016

Line 525:

In the typical case, only the <code>__init__</code> method need be defined. (The most common exception is for immutable objects.)

<source lang="pythonpycon">

>>> class ExampleClass(object):

... def __new__(cls, value):

... print("Creating new instance...")

... # Call the superclass constructor to create the instance.

... instance = super(ExampleClass, cls).__new__(cls)

... return instance

... def __init__(self, value):

... print("Initialising instance...")

... self.payload = value

>>> exampleInstance = ExampleClass(42)

Creating new instance...

exampleInstance = ExampleClass(42)

# prints "Creating new instance..." followed by "Initialising instance..."

>>> print(exampleInstance.payload)

42

print(exampleInstance.payload)

# prints 42

</source>