Python Data Persistence - Getters/setters

Python Data Persistence – Getters/setters

Java class employs getter and setter methods to regulate access to private data members in it. Let us see if it works for a Python class. Following code modifies myclass.py and provides getter and setter methods for my name and my age instance attributes.

Example

#myclass.py
class MyClass:
__slots__=['myname', 'myage']
def__init__(self, name=None, age=None):
self.myname=name
self,myage=age
def getname(self):
return self.myname
def set name(self, name):
self.myname=name
def getage(self):
return self.myage
def setage(self, age):
self.myage=age
def about(self):
print ('My name is { } and I am { } years old' ,format(self.myname,self.myage) )

The getters and setters allow instance attributes to be retrieved / modified.

Example

>>> from myclass import MyClass
>>> obj1=MyClass('Ashok',21)
>>> obj1.getage( )
21
>>> obj1.setname('Amar')
>>> obj1.about( )
My name is Amar and I am 21 years old

Good enough. However, this still doesn’t prevent direct access to instance attributes. Why?

Example

>>> obj1.myname
'Amar'
>>> getattr(obj1,'myage')
21
>>> obj1.myage=25
>>> setattr(obj1myname1, 'Ashok')
>>> obj1.about()
My name is Ashok and I am 25 years old

Python doesn’t believe in restricting member access hence it doesn’t have access to controlling keywords such as public, private, or protected. In fact, as you can see, class members (attributes as well as methods) are public, being freely accessible from outside the class. Guido Van Rossum – who developed Python in the early 1990s – once said, “We ‘re all consenting adults here” justifying the absence of such access restrictions. Then what is a ‘Pythonic’ way to use getters and setters? The built-in property () function holds the answer.

Python Data Persistence – Getters/setters

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