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Learn how to handle errors in Python using `try except` blocks effectively, allowing your scripts to continue execution even when one or more fail.
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This video is based on the question https://stackoverflow.com/q/74267472/ asked by the user 'user540393' ( https://stackoverflow.com/u/9594492/ ) and on the answer https://stackoverflow.com/a/74267531/ provided by the user 'John Gordon' ( https://stackoverflow.com/u/494134/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use Try Except in Python to Allow Your Program to Continue Running After Errors

When coding in Python, one common scenario developers often face is how to handle errors gracefully. If your script runs multiple independent functions, and one of them fails, you want to ensure that the rest continue executing instead of stopping entirely. This is particularly useful for tasks such as data processing where one failure shouldn’t halt the entire operation.

The Problem Statement

In the given scenario, the user is running a sequence of scripts: Script1, Script2, and Script3. The problem arises when Script2 fails due to a FileNotFoundError, halting the entire program. The goal is to adjust the code to allow for error handling so that the failure of one script does not prevent the others from running.

Here’s the relevant error message encountered:

[[See Video to Reveal this Text or Code Snippet]]

Clearly, this indicates that when a script encounters an issue, the program stops executing. Let's explore how to resolve this issue effectively.

Solution Breakdown

The Initial Code Example

The user provided the following code to handle exceptions in Python with try except blocks:

[[See Video to Reveal this Text or Code Snippet]]

Identifying the Issue

The error lies in how the function is being passed to the errorFunction. Specifically, this line:

[[See Video to Reveal this Text or Code Snippet]]

Here, Script1() is being called when it is passed to errorFunction, which means that the script executes before error handling can take place. So, if Script1() has an error, it stops the whole program.

The Fix: Adjusting Function Call Syntax

To fix the code, you need to pass the function itself without calling it immediately. You can do this by removing the parentheses from the function calls like so:

[[See Video to Reveal this Text or Code Snippet]]

In this way, Script1 is passed as a reference, and the errorFunction can execute it later.

Modifying the Try Except Block

Next, within the errorFunction, you will need to ensure that the function is executed properly. Update the try block to call the function, as shown below:

[[See Video to Reveal this Text or Code Snippet]]

Final Revised Code

Combining both modifications, the corrected and functioning version of the code looks like this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By making these simple changes to how functions are called and invoked within the try except structure, you ensure that your Python scripts can run independently of each other. Thus, if one script fails, the other scripts will continue to execute, providing greater stability and reliability in your program flow.

Adopting proper error handling with try except blocks not only improves your script's functionality but also enhances your coding practices in general. Happy coding!