Resolving f-string Syntax Errors: Python 3.5 vs Python 3.8

Learn how to fix Python code that works in version 3.8 but throws a syntax error in version 3.5, using string formatting effectively.
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Resolving f-string Syntax Errors: Python 3.5 vs Python 3.8

If you’re working with Python to automate tasks or analyze data, you might encounter issues related to differing versions. One common problem arises when code that runs smoothly in Python 3.8 stumbles in Python 3.5. This situation can be frustrating, especially when you're bound to an older version due to software compatibility, like in the case of UiPath which only supports Python versions greater than 3.6.

Identifying the Issue

In this instance, the script that runs without a hitch in Python 3.8 is failing with a syntax error in Python 3.5. The error message is quite clear: "invalid syntax". This indicates that there's something in the code that Python 3.5 does not recognize.

Example Code Causing the Error

Here’s the relevant snippet from the script that's causing the problem:

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

The use of fr before the string signifies that it is a formatted string literal, commonly known as an f-string, which was introduced in Python 3.6. Hence, this syntax is not compatible with Python 3.5.

The Solution: Switching String Formatting Methods

To resolve this issue, you can replace the f-string with a different method of string formatting that is compatible with older versions of Python, such as the format() method. Here’s how you can modify the code:

Revised Code

Update the problematic line to the following:

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

Breakdown of the Fix

Remove the fr Prefix: The f indicates the use of f-strings, which are not supported in Python 3.5.

Use format() Method: The .format() method allows us to insert the value of row['Output'] into the string.

Escape Backslashes: In file paths on Windows, ensure that backslashes (\) are escaped by using double backslashes (\), or alternatively, you can use raw strings by prefixing with r.

Advantages of the format() Method

Compatibility: Works seamlessly with older Python versions, making it a safe choice when backward compatibility is a concern.

Flexibility: Allows complex formatting options compared to simple concatenation.

Conclusion

When tackling Python compatibility issues, especially between versions 3.5 and 3.8, understanding the nuances of string formatting is crucial. By replacing f-strings with the format() method, you can ensure your code runs smoothly across different environments without triggering syntax errors.

If you're using Python 3.5 and encounter issues similar to those described here, don't hesitate to revisit your string formatting techniques. Adapting your code in this way not only resolves current issues but also solidifies your understanding of Python's evolution over versions.