How to Verify if an Object is an Instance of a List for a Given Class Name in Python?

How can I check if an object belongs to a list of a specified class in Python?

# Example of checking if an object is an instance of a specific class
if isinstance(obj, YourClass):
    print("obj is an instance of YourClass")

In Python, you can determine whether an object is an instance of a list containing items of a particular class by utilizing the built-in `isinstance()` function in combination with the `all()` function. This approach allows you to iterate through the list and check the type of each element against the specific class you are interested in.

# Function to check if an object is a list of a given class
from typing import List, Type

def is_instance_of_list(obj: List, cls: Type) -> bool:
    return isinstance(obj, list) and all(isinstance(item, cls) for item in obj) 

# Example usage
class MyClass:
    pass

my_list = [MyClass(), MyClass()]  # List of MyClass instances
other_list = [MyClass(), 'NotAClassInstance']  # Mixed types

print(is_instance_of_list(my_list, MyClass))  # Output: True
print(is_instance_of_list(other_list, MyClass))  # Output: False

Causes

• The object is not a list.
• The list contains elements that are not of the specified class.】【[

Solutions

• Use the built-in isinstance() function to confirm the object is a list.
• Utilize a list comprehension or the all() function to ensure all items in the list are instances of the specified class.

Mistake: Assuming all lists are of the correct object type without checking.

Solution: Always verify the type of each item in the list using isinstance().

Mistake: Not handling mixed-type lists.

Solution: Use the all() function to validate all elements in a list.