{"id":555,"date":"2020-10-15T07:25:06","date_gmt":"2020-10-15T07:25:06","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=555"},"modified":"2021-10-25T07:20:27","modified_gmt":"2021-10-25T07:20:27","slug":"python-static-methods","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-oop\/python-static-methods\/","title":{"rendered":"Python Static Methods"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about Python static methods and how to use them to create a utility class.<\/p>\n\n\n\n

Introduction to Python static methods #<\/a><\/h2>\n\n\n\n

So far, you have learned about instance methods that are bound to a specific instance. It means that instance methods can access and modify the state of the bound object.<\/p>\n\n\n\n

Also, you learned about class methods<\/a> that are bound to a class. The class methods can access and modify the class state.<\/p>\n\n\n\n

Unlike instance methods, static methods aren’t bound to an object. In other words, static methods cannot access and modify an object state.<\/p>\n\n\n\n

In addition, Python doesn’t implicitly pass the cls<\/code> parameter (or the self<\/code> parameter) to static methods. Therefore, static methods cannot access and modify the class’s state.<\/p>\n\n\n\n

In practice, you use static methods to define utility methods or group functions<\/a> that have some logical relationships in a class.<\/p>\n\n\n\n

To define a static method, you use the @staticmethod<\/code> decorator:<\/p>\n\n\n

class<\/span> className<\/span>:<\/span>\n    @staticmethod<\/span>\n    def<\/span> static_method_name<\/span>(param_list)<\/span>:<\/span>\n        pass<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
To call a static method, you use this syntax:<\/p>\n\n\n
className.static_method_name()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Python static methods vs class methods #<\/a><\/h2>\n\n\n\n
Since static methods are quite similar to the class methods<\/a>, you can use the following to find the differences between them:<\/p>\n\n\n\n
Class Methods<\/strong><\/th>Static Methods<\/strong><\/th><\/tr><\/thead>
Python implicitly pass the cls<\/code>  argument to class methods.<\/td>Python doesn’t implicitly pass the cls<\/code> argument to static methods<\/td><\/tr>
Class methods can <\/strong>access and modify the class state.<\/td>Static methods cannot <\/strong>access or modify the class state.<\/td><\/tr>
Use @classmethod<\/code> decorators to define class methods<\/td>Use @staticmethod<\/code> decorators to define static methods.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Python static method examples #<\/a><\/h2>\n\n\n\n
The following defines a class called TemperatureConverter<\/code> that has static methods for converting temperatures between Celsius, Fahrenheit, and Kelvin:<\/p>\n\n\n
class<\/span> TemperatureConverter<\/span>:<\/span>\n    KEVIN = 'K'<\/span>,\n    FAHRENHEIT = 'F'<\/span>\n    CELSIUS = 'C'<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> celsius_to_fahrenheit<\/span>(c)<\/span>:<\/span>\n        return<\/span> 9<\/span>*c\/5<\/span> + 32<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> fahrenheit_to_celsius<\/span>(f)<\/span>:<\/span>\n        return<\/span> 5<\/span>*(f-32<\/span>)\/9<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> celsius_to_kelvin<\/span>(c)<\/span>:<\/span>\n        return<\/span> c + 273.15<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> kelvin_to_celsius<\/span>(k)<\/span>:<\/span>\n        return<\/span> k - 273.15<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> fahrenheit_to_kelvin<\/span>(f)<\/span>:<\/span>\n        return<\/span> 5<\/span>*(f+459.67<\/span>)\/9<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> kelvin_to_fahrenheit<\/span>(k)<\/span>:<\/span>\n        return<\/span> 9<\/span>*k\/5<\/span> - 459.67<\/span>\n\n    @staticmethod<\/span>\n    def<\/span> format<\/span>(value, unit)<\/span>:<\/span>\n        symbol = ''<\/span>\n        if<\/span> unit == TemperatureConverter.FAHRENHEIT:\n            symbol = '\u00b0F'<\/span>\n        elif<\/span> unit == TemperatureConverter.CELSIUS:\n            symbol = '\u00b0C'<\/span>\n        elif<\/span> unit == TemperatureConverter.KEVIN:\n            symbol = '\u00b0K'<\/span>\n\n        return<\/span> f'{value}<\/span>{symbol}<\/span>'<\/span>\n<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
And to call the TemperatureConverter<\/code> class, you use the following:<\/p>\n\n\n
f = TemperatureConverter.celsius_to_fahrenheit(35<\/span>)\nprint(TemperatureConverter.format(f, TemperatureConverter.FAHRENHEIT))\n<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
  • Use static methods to define utility methods or group a logically related functions into a class.<\/li>
  • Use the @staticmethod<\/code> decorator to define a static method.<\/li><\/ul>\n
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