Get objects methods python

Get objects methods python

Last updated: Feb 21, 2023
Reading time · 3 min

# Table of Contents

# Get all methods of a given class in Python

Use the inspect.getmembers() method to get all methods of a class.

The getmembers() method will return a list containing all of the methods of the class.

Copied! 
import inspect class Employee(): def __init__(self, name, salary): self.salary = salary self.name = name def get_name(self): return self.name def get_salary(self): return self.salary # ✅ called inspect.getmembers with the class itself list_of_methods = inspect.getmembers(Employee, predicate=inspect.isfunction) # 👇️ [('__init__', ), ('get_name', ), ('get_salary', )] print(list_of_methods) # ------------------------------------------------------------------ bob = Employee('Bobbyhadz', 100) # ✅ called inspect.getmembers with instance of the class list_of_methods = inspect.getmembers(bob, predicate=inspect.ismethod) # 👇️ [('__init__', >), ('get_name', >), ('get_salary', >)] print(list_of_methods) 

We used the inspect.getmembers() method to get a list containing all of the methods of a class.

The inspect.getmembers method takes an object and returns all the members of the object in a list of tuples.

The first element in each tuple is the name of the member and the second is the value.

We set the predicate argument to inspect.function to get a list containing only the methods of the class.

# Passing an instance of the class to inspect.getmembers()

The inspect.getmembers() method can also be passed an instance of a class, but you have to change the predicate to inspect.ismethod .

Copied! 
import inspect class Employee(): def __init__(self, name, salary): self.salary = salary self.name = name def get_name(self): return self.name def get_salary(self): return self.salary bob = Employee('Bobbyhadz', 100) list_of_methods = inspect.getmembers(bob, predicate=inspect.ismethod) # [('__init__', >), ('get_name', >), ('get_salary', >)] print(list_of_methods) 

The inspect.isfunction predicate returns True if the object is a Python function.

The inspect.ismethod predicate returns True if the object is a bound method written in Python.

Make sure to use inspect.isfunction when passing a class to the inspect.getmembers() method and inspect.ismethod when passing an instance to getmembers() .

Alternatively, you can use the dir() function.

# Get all methods of a given class using dir()

This is a three-step process:

1. Use the dir() function to get a list of the names of the class’s attributes.
2. Use a list comprehension to filter out the attributes that start with a double underscore and all non-methods.
3. The list will only contain the class’s methods.

Copied! 
class Employee(): def __init__(self, name, salary): self.salary = salary self.name = name def get_name(self): return self.name def get_salary(self): return self.salary class_methods = [method for method in dir(Employee) if not method.startswith('__') and callable(getattr(Employee, method)) ] print(class_methods) # 👉️ ['get_name', 'get_salary'] 

Filtering out the attributes that start with two underscores is optional.

Make sure to remove the condition if you need to keep method names that start with two underscores.

Copied! 
class_methods = [method for method in dir(Employee) if callable(getattr(Employee, method)) ] # ['__class__', '__delattr__', '__dir__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'get_name', 'get_salary'] print(class_methods) 

The class_methods list contains all the method names of the class.

# Getting all methods of an instance with dir()

You can also use this approach to get all methods of an instance.

Copied! 
class Employee(): def __init__(self, name, salary): self.salary = salary self.name = name def get_name(self): return self.name def get_salary(self): return self.salary bob = Employee('Bobbyhadz', 100) class_methods = [method for method in dir(bob) if not method.startswith('__') and callable(getattr(bob, method)) ] print(class_methods) # 👉️ ['get_name', 'get_salary'] 

You can use the getattr function if you need to call some of the methods.

Copied! 
bob = Employee('Bobbyhadz', 100) class_methods = [method for method in dir(bob) if not method.startswith('__') and callable(getattr(bob, method)) ] print(class_methods) # 👉️ ['get_name', 'get_salary'] method_1 = getattr(bob, class_methods[0]) print(method_1()) # 👉️ Bobbyhadz 

The getattr function returns the value of the provided attribute of the object.

The function takes the object, the name of the attribute and a default value for when the attribute doesn’t exist on the object as parameters.

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

Источник

Print Methods of Object in Python

Working with Python methods and attributes is very easy but seems challenging when we want to know if a specific object has a particular method/attribute or not.

This tutorial teaches the use of dir() , and inspect.getmembers() to print all methods of a Python object. We will also learn how to filter magic methods and check if an attribute is callable or not.

Finally, we will learn hasattr() and getattr() to find a specific attribute of a Python object and its value.

Use dir() to Print All Methods of Python Object

The dir() is a built-in Python function which returns all the attributes and methods (without values) of a specified object. It not only returns the built-in attributes (also known as properties) and methods but we can also get user-defined properties and methods.

To use the built-in dir() method, let’s create a string-type object and name it first_name which will contain a string-type value. Next, we use the dir() method, pass it first_name object, and save the returned output by the dir() method in a new variable, called result .

Finally, we print the values of result to get a list of all the methods and attributes of a Python object, which is first_name here.

[ ‘__add__’ , ‘__class__’ , ‘__contains__’ , ‘__delattr__’ , ‘__dir__’ , ‘__doc__’ , ‘__eq__’ , ‘__format__’ , ‘__ge__’ , ‘__getattribute__’ , ‘__getitem__’ , ‘__getnewargs__’ , ‘__gt__’ , ‘__hash__’ , ‘__init__’ , ‘__init_subclass__’ , ‘__iter__’ , ‘__le__’ , ‘__len__’ , ‘__lt__’ , ‘__mod__’ , ‘__mul__’ , ‘__ne__’ , ‘__new__’ , ‘__reduce__’ , ‘__reduce_ex__’ , ‘__repr__’ , ‘__rmod__’ , ‘__rmul__’ , ‘__setattr__’ , ‘__sizeof__’ , ‘__str__’ , ‘__subclasshook__’ , ‘capitalize’ , ‘casefold’ , ‘center’ , ‘count’ , ‘encode’ , ‘endswith’ , ‘expandtabs’ , ‘find’ , ‘format’ , ‘format_map’ , ‘index’ , ‘isalnum’ , ‘isalpha’ , ‘isascii’ , ‘isdecimal’ , ‘isdigit’ , ‘isidentifier’ , ‘islower’ , ‘isnumeric’ , ‘isprintable’ , ‘isspace’ , ‘istitle’ , ‘isupper’ , ‘join’ , ‘ljust’ , ‘lower’ , ‘lstrip’ , ‘maketrans’ , ‘partition’ , ‘removeprefix’ , ‘removesuffix’ , ‘replace’ , ‘rfind’ , ‘rindex’ , ‘rjust’ , ‘rpartition’ , ‘rsplit’ , ‘rstrip’ , ‘split’ , ‘splitlines’ , ‘startswith’ , ‘strip’ , ‘swapcase’ , ‘title’ , ‘translate’ , ‘upper’ , ‘zfill’ ]

Here, we have retrieved all the attributes and methods, the methods starting and ending with double underscores ( __ ) are called dunder methods or magic methods , which are called by the wrapper functions .

It means dunder or magic methods are not directly invoked by us (the programmers) but their invocation occurs internally from a specific class based on a particular action.

For instance, if we call the dir() method then __dict__() would be invoked behind the scenes. Let’s take another example, where we add two numbers using the + operator, internally, the __add__() method would be called to perform this operation.

As we are not using the magic methods directly so, we can filter them and get a list of methods and attributes that we can directly use from our code. So, let’s dive into the following section to learn how to filter magic methods .

Filter Magic Methods

Here, we use a for loop to iterate over a list returned by dir(first_name) (you can replace first_name with your object) and if statement to filter out magic or dunder methods, we wrap this code with square brackets ( [] ) to get a list type output.

Источник