Override line-length for subdirectories

[aklajnert]

Currently, black allows changing the line length globally via pyproject.toml or with the --line-length argument. This setting is global for the whole directory tree.

In my project, I have a docs/examples directory, which contains python files, that are shown in the documentation by using the literalinclude directive. While for most of the project the global line length setting (100) is fine, for the examples it's too wide and requires the horizontal scroll bar to display the code samples.

I've tried to add another pyproject.toml file in the docs/examples directory, but it is respected only when I'll execute black from that directory. It's hard to use it from pre-commit hooks.

Is there any way to override the line length for subdirectories?

[zsol]

You can specify the location of a config file via the --config command line option, if that helps.

[aklajnert]

A bit. I mean, I can construct pre-commit hooks for that, but I still can't run single black . command to correctly format everything.
It would be nice to automatically load and respect pyproject.toml files in the subdirectories that override certain settings, or allow overrides in the root pyproject.toml similar to how mypy:

[mypy]
python_version = 2.7
warn_return_any = True
warn_unused_configs = True

# Per-module options:

[mypy-mycode.foo.*]
disallow_untyped_defs = True

[JelleZijlstra]

There's been some discussion on the linked PR that's really about whether we should do this at all. That's more appropriate to the issue, so I'm bringing it back here.

@felix-hilden brought up that we may not want this at all as it doesn't go well with our general stance to minimize configurability. I'm sympathetic to that argument, but I do find @aklajnert's use case above compelling.

[felix-hilden]

I tend to agree that line length shouldn't be that big of a deal, since the presented use case is solid.

[JelleZijlstra]

Since this hasn't been a common request and it would complicate our internals, I'm now inclined to reject this enhancement request. We can revisit that decision if we get more use cases.