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In this tutorial we will talk about polymorphism

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in object oriented programming.

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The term polymorphism refers to the ability of an object to attach the cord to the type of the data

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it is processing so let's understand polymorphism.

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Using example.

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Let us add two numbers two and three and I'm using a plus operator to perform the addition operation

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the interpreter to Don's file this case.

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Now let us concatenate two strings hello and whoa.

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And if I want to concatenate two strings I have to use the plus operator again and the interpreter in

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this case

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then we concatenate using the plus operator.

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This is what the interpreter returns.

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Now I want to concatenate to lis in order to concatenate I have to use the plus operator again and the

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output would be one two three.

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And this is the output.

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If you observe carefully the actions performed by the plus operator the addition operator the different

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input parameters.

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So then we pass to indigenous to the plus operator.

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It is doing a mathematical operation when we are passing two strings to the operator to the plus operator.

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It is concatenated ing both of these strings.

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Similarly when we pass to list to the plus operator when we want to continue to list using the plus

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operator it is concatenate taking both the list into a single list.

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No let us come back to the definition or polymorphism the term polymorphism refers to the ability of

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an object to adapt to go to the type of data it is processing and an object may provide different implementations

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of one of its methods depending on the type of the input parameters when we want to perform addition

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between two integers 2 and 3 We know 2 and 3 are instances of the built an integer class and when we

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want to perform this addition operation Python actually looks for a method in the integer class which

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is the underscored underscore and underscored underscore and this method defines the procedure for performing

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addition operation on numbers similarly when we want to concatenate two strings using the plus operator

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we know how low and world instances of these string class which is built in class when we want to concatenate

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these two strings Python looks for the underscore underscored add method in the String class and this

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add method which is defined in the String class gives the procedure to concatenate strings.

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Same is the case when we want to concatenate to list using the plus operator

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so these two lives are instances or copies of the built in class list.

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And when we want to contact an aide using the plus operator Python find for this method at in the list

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class and the method the ad method defined in this list class gives the procedure to concatenate to

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list

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so depending upon the input parameters the definition of the add method which is a special method or

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a magic method is changing.

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Essentially each Burton function or operator has a special method or a magic method corresponding to

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it.

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For example we have the underscored underscored Len underscored underscored corresponding to the length

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function and underscored underscored and underscored underscored with just corresponding to the plus

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operator every class in Python defined its own behavior for building functions and methods.

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And when we pass an instance of some class to a built in function or use an operator on the instance

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like we did here it doesn't actually equal into calling a special method.

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We did elegant argument say for example we have a built in function

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if and C and the corresponding special method for the function is underscored underscore function underscored

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under school and Python interpret a call to the function as

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object dart underscored underscored function underscored underscore in the case of operators.

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If we have an operator like the plus operator say we have the operator or be in the corresponding method

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is underscored underscored or be odd underscored underscore and Biden interpret something like this

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object 1 dart underscored underscored or Pete I'd underscore underscore and object to its past as an

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object

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so when we are adding two numbers two and three using the plus operator this actually gets translated

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in to

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to DOD underscored underscored and underscored underscored.

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And the second number three is parsed as an argument and say for example if we want to if we want to

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calculate the length or the string hello this gets translated to Hello dart underscored underscore Lynn

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underscored underscore and these methods the double underscored method are also called special methods

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in Python and the special method at a set of predefined method which we can use to enrich our classes

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user defined classes so we can define these special methods or the standard methods in our own classes

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we can override the behavior or the function or an operator associated with them because behind the

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scenes python is calling up a method.

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So let us see how we can use the Dando method let's define two variables x and y.

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Now we can use the plus operator in order to add these two integers.

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And this is the result.

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We can also call the add method the double underscored add method which is defined in the integer class

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needed to perform the addition operation.

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But on these two objects.

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So let's do that.

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So when we call the double underscored add method this is the object 1.

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And on this object we're calling the add method and the second object is parsed as an argument.

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So you have the output next let's concatenate.

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Let's concatenate two strings so we will call the add method on this variable e

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so here we have these two strings concatenated using the add method when we use the plus operator to

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perform addition on two integers or concatenate two strings in the background.

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Python is actually making a call to the special method and so polymorphism refers to the ability of

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an object to a daddy go to the type of data it this processing.

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Next is operator overload.

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So what does operator overloading Python makes it possible to change the definition of the building

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operators when they're applied to user defined types.

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And this is called operator overloading the plus operator in these examples has different meaning depending

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on the types of the parameters involved.

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And if python does not recognize the operation and that combination of types we get an error Python

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provides a set of operators that can be overloaded the plus operator is overloaded.

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That means the operator can do odd mean different things depending on the types involved the case if

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the input parameters are integers it performs the addition operation if the input parameters strings

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it concatenate the plus operator concatenate these the strings if the input parameters are list it concatenate

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both the list into a single list and byte and provide the set of operators that can be overlooked.

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So these are some of the operators that can be overloaded.

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That means they perform different operations or mean different things depending on the types input types

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involved so we have the code multiplication operator.

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The subtraction operator code and so on and this is the magic method or the special method corresponding

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to the operators.

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So we have seen the plus operator can be used to add integers and then concatenate strings and also

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list so we have the plus operator that is used to concatenate Delius.

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Now we will define a user defined class and then see if we can use the plus operator to concatenate

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or add to instances of that class

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so here you have two instances of the indigent object X and Y.

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And we have a plus operator not to perform addition operation on these two instances of the integer

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class a and b add to instances of the string class and we can use the plus operator to concatenate these

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strings and here we have two instances of the list class and using the plus operator we have concatenated

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these two strings.

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I'm not going to define a class and see if we can use the plus operator on the instances of the class.

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This is the class got and it has an init method not to initialize the instance variables.

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This class basically maintains the items ordered by a customer in a list so we will create two instances

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of this class got one and got 2 and then use a plus operator in order to contaminate the two instances

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so the items in in these two cards need to be concatenated into a single list.

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So now let's create two cards two instances of the class card let's say the instances card one.

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And the argument that I'm going to pass to the class card is a list so I'm going to pass the element

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light and then lamp switches.

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So in this God I have three elements light lamp and switches.

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So this is got one.

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And in another card.

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Got two.

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I'm going to pass the elements but and then Wyatt so these other two cards.

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Now I want to concatenate the elements in both these cards.

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So can we perform the addition operation on these two objects.

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But before performing the addition operation using the plus operator on these two objects on these two

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instances let us check the type or these two instances.

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Card 1.

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So this is of the type the class card.

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Same is the case with the second card.

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Card 2.

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Now I want to perform or use the plus operator on these two instances.

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And we have a type error here.

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It says unsupported operant type for the plus operator so this basically means Python does not recognize

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the operation.

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And this combination of types that is the type cut that does because we have not defined a method in

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our class card in order to perform addition operation we do not have a special or the magic method at

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which defined these procedure to add to instances of this class card.

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So letters include the add method in this class we have now included the add method the special method

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in our card class the add method takes in to parameters self and other.

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The first parameter is the object on which the add method is invoked.

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The second parameter is named either to distinguish it from sale.

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So in our example self refers to card 1 and either refers to card to now coming to the body of the add

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method we have a return statement and this return statement returns discard object and before that we

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are contaminating the items in card one and card to.

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Now when we perform a mission operation on these two instances let us see that let us use the plus operator

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and on card 1 and card 2 and assign this 2 Card 3.

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Now when we print the card 3.

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So here we have the elements in both the cards got one and card to concatenated.

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That is because we now had an add method the special method and that has given a procedure to concatenate

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the instances got one and got two.

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So we have just overloaded the plus operator by giving it a new definition and numbered.

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Class got.