Скачать или смотреть How to Use table.unpack in Lua 5.4

Learn how to replace the unpack() function in Lua 5.4 with table.unpack. This guide explains the changes and provides examples to help you adapt your code.
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This video is based on the question https://stackoverflow.com/q/65655185/ asked by the user 'user1766438' ( https://stackoverflow.com/u/1766438/ ) and on the answer https://stackoverflow.com/a/65655296/ provided by the user 'Spar' ( https://stackoverflow.com/u/8621712/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the unpack() Function in Lua

If you are familiar with Lua programming, you may have encountered the unpack() function in various guides and examples. Traditionally, this function has been used to take a table and return its elements as individual values. However, with the release of Lua 5.2, changes were made that users need to be aware of, especially when transitioning to Lua 5.4.

In this post, we’ll address a common issue: why you might see the error message "attempt to call a nil value (global 'unpack')" and how to resolve it by using the correct method in Lua 5.4.

The Problem

You may have tried to use unpack() like this:

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Expecting the output to be "the quick brown", you instead encountered an error. This is likely caused by the fact that in Lua 5.4, the unpack() function has been removed from the global scope.

What Happened to unpack()?

Starting from Lua version 5.2, the unpack() function was relocated to the table library. This means that instead of calling unpack() directly, you should now use table.unpack() instead.

The Solution: Using table.unpack

To successfully print the elements of your table in Lua 5.4, modify your code as follows:

Step-by-Step Example

Define your table: The same as before.

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Call table.unpack(): Instead of using unpack(), call the function from the table library.

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Expected Output

When you run the modified code, the output will now correctly display:

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

Conclusion

Transitioning from using unpack() to table.unpack() might seem like a small change, but it’s essential for writing up-to-date Lua code, particularly with the shift to Lua 5.4. Always remember that if you encounter an error regarding unpack(), check to see if you are on Lua version 5.2 or later, and simply switch to using table.unpack.

With this simple adjustment, you're all set to successfully utilize this functionality in your Lua scripts! Happy coding!