Raise an exceptionAs a Python developer you can choose to throw an exception if a condition occurs. Show To throw (or raise) an exception, use the ExampleRaise an error and stop the program if x is lower than 0: x = -1 if x < 0: Try it Yourself » The You can define what kind of error to raise, and the text to print to the user. ExampleRaise a TypeError if x is not an integer: x = "hello" if not type(x) is int: Try it Yourself » Raise, return, and how to never fail silently in Python. I hear this question a lot: “Do I raise or return this error in Python?” The right answer will depend on the goals of your application logic. You want to ensure your Python code doesn’t fail silently, saving you and your teammates from having to hunt down deeply entrenched errors. Here’s the difference between When to raise
Use
Raising an exception terminates the flow of your program, allowing the exception to
bubble up the call stack. In the above example, this would let you explicitly handle Raise is useful in cases where you want to define a certain behavior to occur. For example, you may choose to disallow certain words in a text field:
Raise takes an instance of an exception, or a derivative of the Exception class. Here are all of Python’s built-in exceptions. Raise can help you avoid writing functions that fail silently. For example, this code will not raise an exception if
To cause the
Any time your code interacts with an external variable, module, or service, there is a possibility of failure. You can use Raise in try and exceptTo handle a possible failure by taking an action if there is one, use a
This lets
you If you don’t know that the exception will be a Use
You could also place the print line within the When to returnWhen you use While it’s more idiomatic to For example,
if your Python code is interacting with other components that do not handle exception classes, you may want to return a message instead. Here’s an example using a
Note that when you return an You may also use
Using The most important partSilent failures create some of the most frustrating bugs to find and fix. You can help create a pleasant development experience for yourself and your team by using I write about good development practices and how to improve productivity as a software developer. You can get these tips right in your inbox by signing up below! Which of the following will raise a value error in Python?the raise keyword raises a value error with the message “String can't be changed into an integer”.
What is raising an error Python?Sometimes you want Python to throw a custom exception for error handling. You can do this by checking a condition and raising the exception, if the condition is true. The raised exception typically warns the user or the calling application.
How do you give a raise in Python?The raise keyword is used to raise an exception. You can define what kind of error to raise, and the text to print to the user.
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