Скачать или смотреть Resolving the NameError: A Guide to Correcting Undefined Variables in Your Python Code

Learn how to fix the `NameError: variable name is not defined` error in Python and improve your code organization with this detailed guide.
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This video is based on the question https://stackoverflow.com/q/72352940/ asked by the user 'Ethan' ( https://stackoverflow.com/u/19182817/ ) and on the answer https://stackoverflow.com/a/72353060/ provided by the user 'Gabriel Pellegrino' ( https://stackoverflow.com/u/7067224/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the NameError: A Guide to Correcting Undefined Variables in Your Python Code

When working with Python, you might encounter the frustrating NameError: Variable name is not defined error. This commonly occurs when your code tries to access a variable that hasn’t been defined yet or has been defined improperly. In this guide, we’ll walk you through resolving this issue by correcting some code related to managing shopping lists.

Understanding the Problem

In our scenario, you were trying to implement a simple shopping list manager with nested loops and functions. However, the code you provided contained several undefined variables and improper function calls that resulted in the NameError.

Here are some common causes of NameError:

Attempting to use variables that haven't been defined yet.

Misnaming a variable or using a reserved keyword.

Scope issues where the variable is not accessible in the current function or block of code.

Your Original Code

Below is an excerpt of your original code that led to the NameError:

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

In this code snippet, list is used, which is a reserved keyword in Python. Reusing such keywords can lead to confusion and unexpected behaviors.

Fixing the Code

Let’s transform your code for better organization and functionality. Here’s a step-by-step breakdown of the improvements:

1. Restructuring the Code Flow

Instead of nesting all functions and mixing up the variable scopes, we will restructure the program to clearly manage the user input and the actions taken.

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

Expected actions are handled by the handle_action function which simplifies your main loop logic.

2. Correcting the Update Function

The update functionality needs proper parameters and variable names to avoid confusion:

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

3. The Main Loop for User Input

Here’s how the main loop should look:

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

Summary

By following these structured approaches:

Clear Function Definitions: Use clear and non-reserved names for your variables (like list_number).

Organized Flow Control: Create a central function to handle user actions.

Consistent Loop Execution: Maintain clear conditions to stop the execution of the loop.

These changes not only fix the NameError but also make your code more readable and maintainable. You can now focus on expanding the functionality of your shopping list app without worrying about undefined variables.

If you have any further questions or need additional help, I'm here to assist!