Question

what is property inspector (note-short answer) in python

Answer 1

Answer:

Syntax: property(fget, fset, fdel, doc)

Parameters:

fget() – used to get the value of attribute

fset() – used to set the value of attribute

fdel() – used to delete the attribute value

doc() – string that contains the documentation (docstring) for the attribute

Return: Returns a property attribute from the given getter, setter and deleter.

Note:

If no arguments are given, property() method returns a base property attribute that doesn’t contain any getter, setter or deleter.

If doc isn’t provided, property() method takes the docstring of the getter function.

Example #1: Using property() method

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# Python program to explain property() function  

 

# Alphabet class  

class Alphabet:  

   def __init__(self, value):  

       self._value = value  

         

   # getting the values  

   def getValue(self):  

       print('Getting value')  

       return self._value  

         

   # setting the values  

   def setValue(self, value):  

       print('Setting value to ' + value)  

       self._value = value  

         

   # deleting the values  

   def delValue(self):  

       print('Deleting value')  

       del self._value  

     

   value = property(getValue, setValue, delValue, )  

 

# passing the value  

x = Alphabet('GeeksforGeeks')  

print(x.value)  

 

x.value = 'GfG'

 

del x.value  

Output:

Getting value

GeeksforGeeks

Setting value to GfG

Deleting value

 

Using Decorator:

The main work of decorators is they are used to add functionality to the existing code. Also called metaprogramming, as a part of the program tries to modify another part of the program at compile time.

Example #2: Using @property decorator

class Alphabet:  

   def __init__(self, value):  

       self._value = value  

         

x = Alphabet('Peter')  

print(x.value)  

 

x.value = 'Diesel'

 

del x.value  

Output:

First, specify that value() method is also an attribute of Alphabet then, we use the attribute value to specify the setter and the deleter. Notice that the same method value() is used with different definitions for defining the getter, setter and deleter. Whenever we use x.value, it internally calls the appropriate getter, setter and deleter.

Applications:

By using property() method, we can modify our class and implement the value constraint without any change required to the client code. So that the implementation is backward compatible.

Explanation: