STYLE use yaml anchors in .pre-commit-config.yaml for flake8

[MarcoGorelli]

Instead of duplicating these lines

pandas/.pre-commit-config.yaml

Lines 42 to 45 in e39ea30

	additional_dependencies:
	- flake8-comprehensions==3.1.0
	- flake8-bugbear==21.3.2
	- pandas-dev-flaker==0.2.0

pandas/.pre-commit-config.yaml

Lines 79 to 83 in e39ea30

	additional_dependencies:
	- flake8==3.9.2
	- flake8-comprehensions==3.1.0
	- flake8-bugbear==21.3.2
	- pandas-dev-flaker==0.2.0

we would use a yaml anchor

See here for an example of how that works https://github.com/psf/black/pull/2459/files

---

This would also mean being able to get rid of a big part of https://github.com/pandas-dev/pandas/blob/e39ea3024cebb4e7a7fd35972a44637de6c41650/scripts/sync_flake8_versions.py

[lorenzophys]

@MarcoGorelli a question from a non yaml expert: how would you merge those two lists? I don't believe this will work because additional_dependencies will become nested.

additional_dependencies:  &version_check_dependencies [
    flake8-comprehensions==3.1.0,
    flake8-bugbear==21.3.2,
    pandas-dev-flaker==0.2.0,
]
...
additional_dependencies: 
    - flake8==3.9.2
    - *version_check_dependencies

I cannot think of a way to get the second additional_dependencies to be a list.

[Kunsh-Manghwani]

I have resolved the issue and generated a PR .

[Anupam-USP]

Is this issue still open?

[MarcoGorelli]

yup!

[Anupam-USP]

Can i take? @Kunsh-Manghwani has generated a PR

[MarcoGorelli]

Yes, you can take it, their PR hasn't been active for a while

[MarcoGorelli]

Here's another example: asottile/yesqa#49 (comment)

[navjotbans]

I see this issue is pending since long
I am working on this in parallel if nobody raises a PR for 2-3 more days I would do that 😄

[MarcoGorelli]

Awesome, feel free to open a PR when you want

[navjotbans]

@MarcoGorelli Sure

[trallard]

Hey folks I had a quick look at this and found actually that this does not seem immediately fixable. From the .precommit-config.yaml

 additional_dependencies: 
     - flake8-comprehensions==3.1.0 
     - flake8-bugbear==21.3.2 
     - pandas-dev-flaker==0.2.0 

 additional_dependencies: 
   - flake8==3.9.2 
   - flake8-comprehensions==3.1.0 
   - flake8-bugbear==21.3.2 
   - pandas-dev-flaker==0.2.0 

This entails the creation of an anchor and then merging two lists, however, this is not yet possible. for reference

You can see
yaml/pyyaml#469
yaml/yaml#35
yaml/yaml#48

The examples listed elsewhere in this issue can use an anchor since they reuse the same dependencies without the need of merging/extending lists

[MarcoGorelli]

I see, thanks for looking into this!

I'll have another look next week, but this might need closing by the looks of it

[Skylion007]

You can just use:

 additional_dependencies: 
   - flake8==3.9.2 
   - flake8-comprehensions==3.1.0 
   - flake8-bugbear==21.3.2 
   - pandas-dev-flaker==0.2.0 

for both additional_dependencies. It's not like the flake8 additional requirement will conflict with the flake8 hook. (Just make sure to keep it updated).