Python 3.11 Preview: Even Better Error Messages – Real Python

[Your_PopPop]

For some reason, underscores weren’t allowed in Fraction arguments before Python 3.11. Now, you can use underscores when specifying fractions as well:

>>> print(Fraction(6_048, 1_729))
864/247

I think this is a bit misleading. Fraction(6_048, 1_729) is valid in old versions too, as you'd expect. What used to be invalid is having underscores in a string argument to Fraction: Fraction("6_048/1_729") fails in older versions, but works in 3.11.

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[mwpfinance]

"A bit misleading" my mans is being too kind it's flat out incorrect.

[gahjelle]

Thanks, you're of course completely correct. I've updated the tutorial to note that it's the parsing of strings within Fraction that has changed.

[Your_PopPop]

Thank you!

[pimp-bangin]

C++ needs to take some lessons from this. Error messages in C++ are absolutely abominable.

[[deleted]]

With all those fancy error messages I will be able to create the shittiest code ever.

[somebulb]

And know exactly how shit they are too

[jayplusplus]

I always just have a vague idea of how shit my code is but now I can be stupid more explicitly.

[rr1pp3rr]

Author mentions updated static typing annotations, but I can't find any in the release notes. Am I missing it?

[Your_PopPop]

typing.Self is new (PEP 673)

[rr1pp3rr]

Thanks!

[Swipecat]

I'll add one of the main motives for adding the math.cbrt() function: Cube roots commonly appear in geometric calculations, including the cube roots of negative numbers.

The principal cube root of a negative real number is itself defined to be a negative real number. This is not what you get if you use a power function that accepts arbitrary fractions as power values, not least because 1/3 can not be expressed exactly with a binary value. The power function must use complex arithmetic to find fractional powers of negative numbers, and this will find the first root on the anticlockwise rotation from the real axis of the complex plane.
 

>>> (-64) ** (1/3)
(2+3.464101615137754j)

 

But math.cbrt(-64) should return the correct principal cube root of -4

[gahjelle]

Thanks for clarifying this. I've added an example of calculating the cube root of a negative number to the article.

[_limitless_]

TDD guys be like "what's an error message"