Proposal: format GDB Python files with black

[Simon Marchi]

Hi all,

A few people I talked to about this and I have good experience with the
tool black to auto-format Python code.  It is simple to use, fast and
reliable (if it detects that it changed the meaning of the program by
mistake, internal-errors out).  I don't think I need to spell out the
advantage of using such a tool, but just in case: it removes all the
overhead of thinking about formatting when writing or reviewing code.

My suggestion would be to format our code with black all at once.  The
typical counter-argument to this is "it will be harder to use
git-blame".  I don't think this is true, because you need to be able to
skip over commits anyway, and it's trivial to skip over a commit when
git-blaming using an interactive tool.  But it's also possible to tell
git to ignore certain commits when git-blaming [2], so we can do that.

I think the output of black is quite readable.  When it does weird
stuff, it's generally because the lines / expressions are two long
anyway, and deserve to be split in multiple lines / expressions.  Here's
a branch that shows how it would look like:

  https://sourceware.org/git/?p=binutils-gdb.git;a=shortlog;h=refs/heads/users/simark/black

If the feedback is overall positive, I'll send a more format patch.

Simon

[1] https://github.com/psf/black
[2] https://github.com/psf/black#migrating-your-code-style-without-ruining-git-blame