‘Builtin_Function_or_Method’ Object is Not Subscriptable
Python, just like any other programming language, comes with a variety of built-in methods and functions. These are integral parts of the language that provide particular functionalities out of the box.
Built-in functions are global functions provided by Python, and examples of these include print(), len(), and type(). However, they do not belong to any specific data type.
On the other hand, built-in method objects are associated with specific types like strings or lists, and they are accessed using the dot operator. For instance, append() is a built-in method of the list class, strip() is a built-in method of the string class.
What does it mean for an object to be subscriptable?
The term “subscriptable” may sound complex, but it’s rather straightforward once we understand its practical application. In Python, an object is considered subscriptable if it can use index notation – the [] brackets.
For instance, lists, tuples, and dictionaries are all examples of subscriptable objects. In the case of lists, we’re allowed to utilize indices to access and even modify specific elements. An example could be my_list[0] = ‘new value’.
Common Causes of the Error
While tackling Python programming, we may encounter the “builtin function or method object not subscriptable” error quite often. Let’s delve into understanding some common scenarios that lead to this error and effectively demystify them.
Invalid Use of Built-In Functions or Methods
Built-in functions are inherent to Python. They’re programmed to carry out specific tasks. Inappropriate utilization of these builds can lead to the aforementioned error.
Take this example. If we mistakenly call len as len[], the Python interpreter throws the “builtin function or method object not subscriptable” error. That’s due to len being a built-in function and it’s being wrongly called with subscript notation [].
Incorrect Indexing
Indexing allows us to access specific elements within an iterable, like a list or a tuple, in Python. When we try to access an index that doesn’t exist in our data structure, we’re greeted by our unwelcome friend – the “builtin function or method object not subscriptable” error.
Here’s an example. If we have a list list1 = [1, 2, 3] and we try to access list1[3], we’ll face the error. Why? Python starts indexing from 0, so index 3 does not exist in our three-element list.
Incorrect Use of Square Brackets
Square brackets denote indexing or slicing in Python. If we use them incorrectly, we invite the error into our code.
Take a scenario where we are trying to execute a function, but mistakenly use brackets [] instead of parentheses (). For example, if we want to execute a function func() but end up writing func[], Python will return the “builtin function or method object not subscriptable” error because we incorrectly used square brackets.
Preventing the Error
Our keen focus on reliably writing Python code means proactively preventing the “builtin function or method object not subscriptable” error is on top of our list. There are effective methods we can use to steer clear of this common pitfall. Let’s delve deeper into them.
Double-checking Function or Method Usage
Firstly, we’ll address the misuse of built-in functions or methods. Python, like any other programming language, has specific rules about how we can use its built-in functions or methods. These generally cannot be used as lists or tuples. Misunderstanding this leads to our dreaded “not subscriptable” error.
To avoid this, we should double-check our code. Did we accidently use a function sort() or filter() where a list or tuple was needed? Correcting such instances in the code can help prevent this error.
Using Proper Index Values
The second common cause of our error is incorrect indexing. Again, Python has clear rules on how to use indexes with list-like objects. Index values should always be integers, and within the bounds of the size of the object. Our not subscriptable error can be caused by an incorrect index.
We can circumvent this by using correct indexing conventions in our code. We need to note that indexing in Python starts at 0, not 1. Also, we need to make sure we do not use indices that are out of range. These steps will go a long way in keeping our code error-free.
Ensuring Correct Bracket Usage
Thirdly, our use of square brackets is crucial in Python. Incorrect use of square brackets like using them with inappropriate objects can trigger our error.
To ward off this, we should always make sure that our code uses square brackets appropriately. This means using brackets only when we’re certain that the objects are of the correct type, like lists, tuples, or dictionaries. Taking this precaution will ensure our code runs smoothly and steers clear of the “not subscriptable” trap.
