The primary purpose of the Getter and Setter in object-oriented programs is to ensure data encapsulation or hiding. But in python Getter and Setter works a little differently as Private variables in python are not really hidden and can be accessed from outside.
As a result getter and setter are usually used for setting but validation and logic for class field and to avoid direct access.
This Getter and setter property can be achieved in many ways using python
Using the normal functions with predefined nomenclature
Using property() method Python Built-in Functions
Using @property decorators
Using the normal functions with predefined nomenclature
According to nomenclature any function or variable with a double underscor e is a private function for a class.
Example:
__name = 'vinayak'
## or
def __my_name():
return "vinayak"
and any method with get and set append in front is treated as the getter and setter methods for that variable.
class Student(object):
def __init__ (self, name: str) -> None:
self.name: str = name
self.__marks: int = 0
def set_marks(self, marks: int):
"""
setter method
Set Method in python
"""
self.__marks = marks
def get_marks(self):
"""
getter method
Get Method in python
"""
return self.name + " got " + str(self.__marks)
def __str__ (self) -> str:
return "student name is " + self.name
s = Student("vinayak")
print(s)
s.set_marks(10)
marks_s_got = s.get_marks()
print(marks_s_got)
Output:
student name is vinayak
vinayak got 10
Using property() method Python Built-in Functions
property() method in python takes four arguments fget , fset , fdel , and doc where fget is used to retrieve an attribute value, fset is used to set a value for an attribute, and fdel to delete attribute value, whereas the doc is just a docstring for attribute.
class Student(object):
def __init__ (self, name: str) -> None:
self.name: str = name
self.__marks: int = 0
def set_marks(self, marks: int):
"""
setter method
Set Method in python
"""
self.__marks = marks
def get_marks(self):
"""
getter method
Get Method in python
"""
return self.name + " got " + str(self.__marks)
def del_marks(self):
"""
Del Method
"""
self.__marks = 0
return 1
def __str__ (self) -> str:
return "student name is " + self.name
docString = "getter and setter for marks variable"
marks = property(get_marks, set_marks, del_marks, docString)
s = Student("vinayak")
print(s)
s.marks = 10
marks_s_got = s.marks
print(marks_s_got)
del s.marks
print(s.marks)
Output:
student name is vinayak
vinayak got 10
vinayak got 0
Using @property decorators
As we have seen the property() method, the same set of behaviour can also be achived by property decorators. @property decorators is one of the python's built-in decorators.
class Student(object):
def __init__ (self, name: str) -> None:
self.name: str = name
self.__marks: int = 0
@property
def marks(self):
"""
getter method
Get Method in python
"""
return self.name + " got " + str(self.__marks)
@marks.setter
def marks(self, marks: int):
"""
setter method
Set Method in python
"""
self.__marks = marks
@marks.deleter
def marks(self):
"""
Del Method
"""
self.__marks = 0
return 1
def __str__ (self) -> str:
return "student name is " + self.name
s = Student("vinayak")
print(s)
s.marks = 10
marks_s_got = s.marks
print(marks_s_got)
del s.marks
print(s.marks)
Output:
student name is vinayak
vinayak got 10
vinayak got 0
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