Difference Between Function and Method in Python
The enthusiastic learners who choose to learn Python after a thorough understanding of Java programs may know that a group of statements is called a method if it is enclosed and performs a particular task. In the same sense, you tend to use the ‘method’ and ‘function’ interchangeably. However, though both appear to be similar, unlike Java programs, there is a subtle difference between function and method in Python.
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Python functions
A group of organized program statements that perform a specific and relevant task and can be used again and again in the program is called Python’s function. There are three types of functions in Python, namely Built-in or library functions, User-defined functions and Anonymous functions. Python has 69 in-built functions.
Its name can independently call a function. It may or may not have several parameters or no parameters at all. The passing of data is explicit. Data may or may not be returned in a function. No concept class or instance of a class is involved in a function.
Let’s have a brief look at the rules to be followed to define a Python function:
- ‘def’ is the keyword that precedes the function name followed by parentheses before starting the function block.
- The parentheses can accept any number of arguments or parameters.
- Every function’s block code is initiated by a colon (:)
- The value can be returned by a ‘function’ with a ‘return’ statement, which is not mandated.
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What is a method in Python?
A ‘method’ is a function that is associated with a class or an object. The’ method’ is always dependent on the class to which it is associated. The parameters are implicitly passed on to the invoked object. The data in the class to which it is associated can be operated by the method.
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Function v/s Method:
Though function and method are similar by syntax and structure and have a similar execution path, the significant difference between the two lies in the concept of ‘class and its object’. As mentioned earlier, the functions are independent. As they do not associate with any class or object, they can only be invoked by their names. However, this is not the case while a method is called. ‘Methods’ cannot be called by mentioning their names alone. The class to which the particular ‘method’ is associated should be invoked by reference to execute a method. Therefore, it is clearly evident that methods are defined within specified classes, and hence they are always dependent functions. So, it is rightly said that a method is a class dependent function’.
Both procedural and object-oriented programming is possible with Python. Common tasks can be placed within a function while formulating a procedural program and can be called with the name of the function. However, while an object-oriented code is written, ‘methods’ can be used to write the code of the logic. These methods can be called using the objects of the class to which they are associated.
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Summary of Difference between function and method in Python
| Methods | Functions |
| Methods are always defined within a class. | Classes are not required to define a function. |
| Methods are linked to the objects of the class in which they are defined. | Functions are independent of objects as they are not defined within a class. |
| A method cannot be invoked by calling its name alone. The class to which it belongs should be invoked. | Functions can be invoked just by calling their names. |
| Methods can execute the logic with the data enclosed in the object of the class to which it is associated. | Functions perform their operation on the data that the user passes as arguments or parameters. |
| These are the class dependent entities of a Python code. | These are independent entities of a Python code. |
| The first argument of a method should be ‘self’. | ‘Self’ parameter is not required in the case of functions. Functions may have zero or many arguments. |
| Methods are applicable only for object-oriented programming languages. | Functions can be used for both object-oriented and non-object-oriented programming languages. Non-object-oriented programming languages are referred to as procedural programming languages. |
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