Not implementation error python

Sep 22, 2021 12:21:41 PM | Python Exception Handling – NotImplementedError

Struggling with a NotImplementedError in your code? In this blog, we’ll go over what it is, how to raise it, and how to handle it.

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Today, we’re making our way through our in-depth Python Exception Handling series, and we’ll dive into the NotImplementedError in Python. The NotImplementedError is commonly raised when an abstract method is not implemented in a derived class.

Throughout this post, we’ll examine the NotImplementedError in more detail, starting with where it sits in the larger Python Exception Class Hierarchy. We’ll also look at raising this error, how to handle it, and how Airbrake can help you find this error quickly.

Like most Python errors, the NotImplementedError derives from the BaseException, more specifically from the RuntimeError class.

The NotImplementedError is, fortunately, a non-fatal error. It won’t stop your application from running, but it’s always best to clear errors before they cause issues.

What is the NotImplementedError?

According to Python, the NotImplementedError occurs when an abstract method lacks the required derived class to override this method, thus raising this exception.

Let’s break this down a bit.

While it doesn’t provide abstract classes, Python allows you to use its module, Abstract Base Classes (ABC). Abstract classes are helpful because they create blueprints for other classes and establish a set of methods.

An Abstract Base Class includes one or more abstract methods (methods that have been declared but lack implementation). Subclasses, or child classes, are necessary to implement these abstract methods.

To summarize, you’ll see the NotImplementedError two reasons:

1. When you need a derived class to override the abstract method
2. When the implementation is still missing

Now that you know what a NotImplementedError is and why it happens, here’s what you need to do to raise this exception.

How to Raise a NotImplementedError Exception

The NotImplementedError is part of Python’s BaseException, meaning it is a built-in exception. Like with all BaseExceptions, you can raise a NotImplementedError exception.

Raise the NotImplementedError like so:

It’s that simple. But imagine having to raise every exception in a similar fashion manually? It’s a time-consuming process. Save time and find Python errors more quickly with Airbrake Error Monitoring.

How to Handle a NotImplementedError

If you run into the NotImplementedError, the recommended way to handle it is to implement the abstract method for which the error is being raised. Because the NotImplementedError is user-defined, Python can’t raise this error on its own. So, you’ll need to raise it by a package you’re using or code your team wrote. Once you’ve raised it, you can then implement whatever’s missing.

Let’s refer back to this screenshot:

In its current form, you’ll raise a NotImplementedError. All you need to do to handle this error is implement the howl function by a subclass before it’s used.

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Python NotImplementedError

Python NotImplementedError Exception occurs at runtime when client characterized base classes; conceptual techniques should raise this exception when they require inferred classes to abrogate the strategy or while the class is being created to demonstrate that the genuine usage despite everything should be included. This does not have a valid syntax as it is an exception runtime error. This ought not to be utilized to show that an administrator or technique isn’t intended to be bolstered by any means; all things considered, either leave the administrator or strategy unclear or, if a subclass, set it to None.

An exception is an occasion that happens during the execution of a program that disturbs the program’s directions’ ordinary progression. By and large, when a Python content experiences a circumstance that it cannot adapt to, it raises an exception. An exception is a Python object that speaks to a mistake. When a Python content raises an exception, it should either deal with the exemption promptly else it ends and stops.

How NotImplementedError Works in Python?

Now we look at how these NotImplementedErrors or exceptions work in Python.

Example

class BaseClass(object): def __init__(self): super(BaseClass, self).__init__() def do_something(self): raise NotImplementedError(self.__class__.__name__ + '.try_something') class SubClass(BaseClass): def do_something(self): print (self.__class__.__name__ + ' trying something!') SubClass().do_something() BaseClass().do_something() 

Code Explanation: In the above program, we first define an abstract class as our base class. In the main class, we define the interface using the init function and declare an index called self. Once this interface is defined in the base class, it gets prepared to be implemented as soon as we provide the command to define the interface. Soon after this is done, we immediately raise a NotImplementedError, preventing this interface from implementing the command. Hence, when we give the command to ‘try something, it automatically terminates from the abstract class. Then we define the subclass, and we again implement the interface and this time, the implementation works, and it produces the output saying that the subclass is trying something, and it raises the NonImplementation error for the base class and asks us to traceback to this exception.

How to Avoid NotImplementedError in Python?

There are a few circumstances where runtime errors are probably going to happen. At whatever point we attempt to peruse a document or get a client’s contribution, quite possibly something startling will occur – the record may have been moved or erased, and the client may enter information that is not in the correct organization. Great developers should add shields to their projects so regular circumstances like this can be taken care of effortlessly and a program that crashes at whatever point it experiences an effectively predictable issue is not extremely lovely to utilize. Most clients anticipate that projects should be sufficiently strong to recuperate from these sorts of difficulties. Hence, we see various aspects on how to prevent these runtime errors or NotImplementedErrors in Python. There are 2 functions that help in preventing these runtime errors, and they are “try” and “except”.

Example

try: salary = int(input("Enter salary: ")) print("So cool you earn %d amount." % salary) except ValueError: print("Hey, that wasn't a number!") 

Code Explanation: In the above code, we realize that the blunder is probably going to happen when we attempt to change over the client’s contribution to a number. On the off chance that the info string is definitely not a number, this line will trigger a ValueError – that is the reason we indicated it as the sort of blunder that we are going to deal with. We could have determined a progressively broad sort of mistake – or even left the sort out totally, which would have caused to coordinate any sort of exemption – yet that would have been an impractical notion. Imagine a scenario where we got a totally unique mistake that we had not anticipated. It would be dealt with also, and we would not see that anything abnormal was turning out badly. We may likewise need to respond in various manners to various types of blunders. We ought to consistently attempt to pick explicit as opposed to general mistake types for our with the exception of statements. Hence there will not be a runtime error like a NotImplementedError or Value error.

Conclusion

Hence, I conclude by saying that when NotImplementedErrors or exceptions occur in Python during runtime, it will not be interchangeable, and thus the normal implementation is not accepted. This kind of exceptions and errors can be handled by try and except blocks. In NotImplementedError, base classes have unique techniques which will raise this special case when they require determined classes to supersede the strategy or while the class is being created to show that the genuine usage despite everything should be included.

Recommended Articles

This is a guide to Python NotImplementedError. Here we also discuss the introduction and how notimplementederror works in python, along with an example and its code implementation. you may also have a look at the following articles to learn more –

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