In Python, the subscriptable objects, i.e., list, string, dictionary, tuple, etc. are only accessed using square brackets. However, when the built-in methods or functions are accessed using a square bracket, the “built_function_or_method object is not subscriptable” error occurs in Python. To solve this error, Python provides several solutions discussed in this guide. The content of the post is as follows:
- Reason: Use Square Bracket to Call a Builtin Function or Method
- Solution: Use Parentheses Instead of Square Brackets
- Alternate Solution: Use Parentheses to Accessed User-Defined Functions
- Example: Use Parentheses to Pass a List as a Function Argument
Reason: Use Square Bracket to Call a Builtin Function or Method
The main reason which causes this error in the Python program is when a user tries to call a built-in method or function using a square bracket. As we know, calling a function or method is impossible using a square bracket; it will generate a “Not subscriptable” error in Python as shown below:
The above reason snippet shows the “TypeError” when the function is called using a square bracket instead of parentheses.
Solution: Use Parentheses Instead of Square Brackets
To resolve this error, make sure to use parentheses instead of square brackets while calling the built-in method or function in Python. The correct code is shown in the below code block:
Code:
list_value = ['python', 'and', 'linux']
list_value.pop(0)
print(list_value)
In the above code, the list is created, and the “list.pop()‘ function is used to delete the specific item from the index position “0” of the input list.
Output:
The element at the index position “0” has been removed using the “list.pop()” function.
Alternate Solution: Use Parentheses to Accessed User-Defined Functions
The user-defined function is defined in the program using the prefix keyword “def” in Python. To call the user-defined function, we use parentheses instead of the square bracket and store it in a newly created object variable. An example of this solution is shown in the below snippet:
Code:
def sample_list():
return ['python', 'ubuntu', 'linux']
list_1 = sample_list()
print(list_1)
In the above code, the user-defined function “sample_list” is defined in the program. The function is accessed using parentheses. The return value of the function is kept in a variable named “list_1”.
Output:
The value returned by the function is shown successfully on the output without any error.
Example: Use Parentheses to Pass a List as a Function Argument
In the example code given below, the parentheses are used to call the function on the list. Ensure that a list is passed as an argument to a function to avoid an error:
Code:
list_value = []
list_value.extend(['Python', 'Guide', 'Linux'])
print(list_value)
In the above code, an empty list is created at the start of the program. The “list.extend()” function calls on the newly initialized list created inside the function’s parentheses.
Output:
The above output shows that the function successfully extended the list (a list passed as an argument to a function) into an empty list.
Conclusion
The error “builtin_function_or_method’ object is not subscriptable” occurs when a user tries to call the built-in method or function using a square bracket. To fix this error, use parentheses instead of the square bracket to access the built-in method or function in Python. Moreover, the brackets cannot be used to call a user-defined function whose solution is also provided. Multiple solutions have been explained in this Python blog post to handle this “builtin_function_or_method’ object is not subscriptable”.
