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Michael #1: PEP 798: Unpacking in Comprehensions
Brian #2: Pandas 3.0.0rc0
- Pandas 3.0.0 will be released soon, and we’re on Release candidate 0
- Here’s What’s new in Pands 3.0.0
- Dedicated string data type by default
- Inferred by default for string data (instead of object dtype)
- The str dtype can only hold strings (or missing values), in contrast to object dtype. (setitem with non string fails)
- The missing value sentinel is always NaN (np.nan) and follows the same missing value semantics as the other default dtypes.
- Copy-on-Write
- The result of any indexing operation (subsetting a DataFrame or Series in any way, i.e. including accessing a DataFrame column as a Series) or any method returning a new DataFrame or Series, always behaves as if it were a copy in terms of user API.
- As a consequence, if you want to modify an object (DataFrame or Series), the only way to do this is to directly modify that object itself.
- pd.col syntax can now be used in DataFrame.assign() and DataFrame.loc()
- You can now do this:
df.assign(c = pd.col('a') + pd.col('b'))
- New Deprecation Policy
- Plus more
-
Michael #3: typos
Like codespell, typos checks for known misspellings instead of only allowing words from a dictionary. But typos has some extra features I really appreciate, like finding spelling mistakes inside snake_case or camelCase words. For example, if you have the line:
*connecton_string = "sqlite:///my.db"*
codespell won't find the misspelling, but typos will. It gave me the output:
*error: `connecton` should be `connection`, `connector`
╭▸ ./main.py:1:1 │1 │ connecton_string = "sqlite:///my.db"
╰╴━━━━━━━━━*
But the main advantage for me is that typos has an LSP that supports editor integrations like a VS Code extension. As far as I can tell, codespell doesn't support editor integration. (Note that the popular Code Spell Checker VS Code extension is an unrelated project that uses a traditional dictionary approach.)
For more on the differences between codespell and typos, here's a comparison table I found in the typos repo: https://github.com/crate-ci/typos/blob/master/docs/comparison.md
By the way, though it's not mentioned in the installation instructions, typos is published on PyPI and can be installed with uv tool install typos, for example. That said, I don't bother installing it, I just use the VS Code extension and run it as a pre-commit hook. (By the way, I'm using prek instead of pre-commit now; thanks for the tip on episode #448!) It looks like typos also publishes a GitHub action, though I haven't used it.
Brian #4: A couple testing topics
- slowlify
- suggested by Brian Skinn
- Simulate slow, overloaded, or resource-constrained machines to reproduce CI failures and hunt flaky tests.
- Requires Linux with cgroups v2
- Why your mock breaks later
- Ned Badthelder
- Ned’s taught us before to “Mock where the object is used, not where it’s defined.”
- To be more explicit, but probably more confusing to mock-newbies, “don’t mock things that get imported, mock the object in the file it got imported to.”
- See? That’s probably worse. Anyway, read Ned’s post.
- If my project
myproduct has user.py that uses the system builtin open() and we want to patch it:
- DONT DO THIS:
@patch("builtins.open")
- This patches
open() for the whole system
- DO THIS:
@patch("myproduct.user.open")
- This patches
open() for just the user.py file, which is what we want
- Apparently this issue is common and is mucking up using
coverage.py
Extras
Brian:
Michael:
Joke: tabloid - A minimal programming language inspired by clickbait headlines
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