Python dir() method: List all attribute (method) names of an object

The __dir__() method in Python is a special method that, when implemented, returns a list of attribute names for an object. If the __dir__() method is not implemented for a class, Python provides a default implementation that returns the list of attributes of the object, including the attributes from its class and its base classes.

Here's a step-by-step tutorial on how to use the __dir__() method in Python:

Define a class without the __dir__() method: Create a class with an __init__() method to initialize some instance attributes.

class Person:
    def __init__(self, name, age, occupation):
        self.name = name
        self.age = age
        self.occupation = occupation

Create an instance of the class: Instantiate the class to create an object with specific attribute values.

person = Person("Alice", 30, "Software Engineer")

Use the built-in dir() function: When you call the built-in dir() function on an object without a custom __dir__() method, Python uses the default implementation.

print(dir(person))

Output:

['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'age', 'name', 'occupation']

Define a class with the __dir__() method: Create a class with an __init__() method, some instance attributes, and a custom __dir__() method.

class CustomPerson:
    def __init__(self, name, age, occupation):
        self.name = name
        self.age = age
        self.occupation = occupation

    def __dir__(self):
        return ["name", "age", "occupation", "custom_attribute"]

Create an instance of the CustomPerson class: Instantiate the CustomPerson class to create an object with specific attribute values.

custom_person = CustomPerson("Bob", 35, "Data Scientist")

Call the dir() function on the CustomPerson instance: When you call the dir() function on an object with a custom __dir__() method, Python uses the custom implementation.

print(dir(custom_person))

Output:

['age', 'custom_attribute', 'name', 'occupation']

In this tutorial, you learned how to use the __dir__() method in Python to customize the output of the built-in dir() function for a class. By implementing a custom __dir__() method, you can control the list of attributes displayed when the dir() function is called on an instance of your class. This can be useful for providing a cleaner interface or for hiding certain attributes from the user.

How to use dir in Python to list object attributes:

class SampleObject:
    def __init__(self, x, y):
        self.x = x
        self.y = y

obj = SampleObject(42, "Hello")
attributes = dir(obj)
print(attributes)

Inspecting object attributes with dir:

class InspectableObject:
    def __init__(self, a, b):
        self.a = a
        self.b = b

obj = InspectableObject(10, "World")
attributes = dir(obj)
print(attributes)

Listing methods of an object using dir in Python:

class MethodObject:
    def method1(self):
        pass

    def method2(self):
        pass

obj = MethodObject()
methods = [method for method in dir(obj) if callable(getattr(obj, method))]
print(methods)

Customizing attribute listing with dir:

class CustomDirObject:
    def __dir__(self):
        return ["custom_attr", "another_attr"]

obj = CustomDirObject()
attributes = dir(obj)
print(attributes)

Dynamic attribute management with dir in Python:

class DynamicDirObject:
    def __dir__(self):
        return [f"attr_{i}" for i in range(5)]

obj = DynamicDirObject()
attributes = dir(obj)
print(attributes)

Exploring object properties with dir:

class PropertyObject:
    @property
    def computed_property(self):
        return "Computed Value"

obj = PropertyObject()
attributes = dir(obj)
print(attributes)

Object introspection using Python dir method:

class IntrospectableObject:
    def __init__(self, x, y):
        self.x = x
        self.y = y

obj = IntrospectableObject(42, "Hello")
attributes = dir(obj)
print(attributes)

Filtering attributes with dir in Python:

class FilteredAttributesObject:
    def __init__(self, a, b):
        self.a = a
        self.b = b

obj = FilteredAttributesObject(10, "World")
attributes = [attr for attr in dir(obj) if not attr.startswith("_")]
print(attributes)

Using dir for debugging in Python:

class DebuggableObject:
    def __init__(self, x, y):
        self.x = x
        self.y = y

obj = DebuggableObject(3, 7)
attributes = dir(obj)
print(attributes)

Accessing hidden attributes with dir:

class HiddenAttributesObject:
    def __init__(self, x, y):
        self._x = x
        self._y = y

obj = HiddenAttributesObject(5, 10)
hidden_attributes = [attr for attr in dir(obj) if attr.startswith("_")]
print(hidden_attributes)

Interactive object exploration with dir:

class InteractiveObject:
    def __init__(self, a, b):
        self.a = a
        self.b = b

obj = InteractiveObject(20, "Python")
print("Interactive exploration:")
for attribute in dir(obj):
    value = getattr(obj, attribute)
    print(f"{attribute}: {value}")

Advanced usage of dir in Python:

class AdvancedDirObject:
    def __dir__(self):
        original_attributes = set(dir(self))
        custom_attributes = {"custom_attr1", "custom_attr2"}
        return list(original_attributes.union(custom_attributes))

obj = AdvancedDirObject()
attributes = dir(obj)
print(attributes)

Python __dir__() method: List all attribute (method) names of an object

Python dir() method: List all attribute (method) names of an object