--include= and --exclude=

[ambv]

I always steered people towards find | grep -E | grep -Ev | xargs black to do custom file matching. But that doesn't work on Windows. We need support for --include= and --exclude= within Black.

They hold regular expressions. The former is "what gets included on recursive searches", the latter "what gets dropped on recursive searches". You can pass multiple --include and multiple --exclude. Checks for --exclude are done first, checks for --include later.

--include= would have a default that is now stores in PYTHON_EXTENSIONS (".pyi?$" in regex form)
--exclude= would have a default that is now stored in BLACKLISTED_DIRECTORIES

This functionality is required by pypa/pip#5425.

[autophagy]

@ambv I have couple of implementation detail questions about this:

• This regex should be applied on the entire path when considering whether to include/exclude something, correct? Not just the name (as is currently done with the includes). So one could pass test\/secrets to --exclude and it would drop files/test/secrets/* but not files/test/notsecrets/?
• I'm wondering how to handle directories in the regexes. Initially, I though something like build\/ would be fine, but pathlib strips trailing slashes from the path. I'd prefer to do it this way, since \/build doesn't always work (if its a directory at the root of wherever black is searching from, the path will just be ('build') - do you think it be sensible to just append a '/' to the path when applying the regex if the child is a directory?

[ambv]

Re 1: Agreed.

Re 2: Yes, your suggestion is good to append / when we discover entry.is_dir() :-)