How to Use a Variable from a Class in Another Page in Python

Learn how to properly access and use instance variables from a class in another page in Python, even as a beginner. This guide provides clear steps using examples.
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How to Use a Variable from a Class in Another Page in Python

As a newcomer to programming, it can be challenging to navigate the complexities of object-oriented programming (OOP) in Python. One common issue that beginners face is how to access a variable (or a method) from a class defined in one file, while trying to use it in another file. This guide addresses this specific problem, ensuring you become more comfortable with OOP concepts in Python.

The Problem

Consider the following class definition in Python:

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

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Attempting to run this code results in an error: "usdcurrency() missing 1 required positional argument: 'self'". This error occurs because usdcurrency() is an instance method, meaning it needs to be called on an instance of the smallwavesincurrency class.

The Solution

So how can you correctly access usdcurrency? Here are three different approaches to solve this problem:

1. Create an Object and Call the Method

The most straightforward method is to create an instance of the smallwavesincurrency class and then call the usdcurrency() method on that instance:

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In this code:

An instance named swic is created, which allows you to access the instance methods and variables.

2. Call the __init__() and usdcurrency() Methods at the Same Time

Another way to achieve this is to call both the constructor and the method in one line:

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In this approach:

You instantiate smallwavesincurrency and immediately call the usdcurrency() method, simplifying your code.

3. Pass a Smallwavesincurrency Object to the Method

The final method involves passing an instance of smallwavesincurrency directly into the usdcurrency method:

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

This option is less common and generally less intuitive, but it demonstrates another way to interact with the instance methods.

Conclusion

Understanding how to properly access instance variables and methods across different files in Python is crucial as you continue to improve your programming skills. By following the approaches outlined above, you can avoid common pitfalls and improve your project structure. Remember to keep experimenting and practicing, as that’s how you truly learn and solidify your understanding of programming concepts!

Happy coding!