I would be a bit surprised if this is true, because it implies that when you're writing code that will be formatted you do not think of the reader's experience.

This could be the case if you have extreme confidence in the formatter, but I have def seen some very funky black outputs. It seems like when writing people will likely do so with a model of how black will yield the final code in mind. (Eg "if I add more characters to this one line list statement, it will get exploded across 5 lines", and affect readability, etc..)

Formatters don't have the understanding like the developers do. Certain changes that might increase the understandability for a human might get obliterated if they don't conform to the rules of the autoformatter.

Rather than “writing... with a model of how black will yield the final code in mind,” it’s more like “Oh, shit, Black made a real mess of this. Can I fix this without butchering the code?”

Yeah--we're basically second-order black formatters now. Not writing code that looks nice, but writing code so a tool that writes code will make it look nice.

Not really. At least that wasn't my intention to say that. Most of the time, I find Black does a Good Enough Job(tm) that I don't care to mess with it.

I agree with sentiment but I don't think it's entirely true that it only affects reading code. When it comes to modifying existing code, I have to deal with whatever format the existing code was written in. For example, personally I hate working with code with tabs so I would find this frustrating. (As an aside, I'll admit this is really my problem and a rather silly one.) Of course one solution is to transform code on read to the current user's preferred format and then back to the canonical format on commit. Although this seems potentially error prone.

> When it comes to modifying existing code

You don't have to deal with anything as long as you're using the same formatter everyone else is using.

My point was that when writing new code, I can write it in whatever format I want knowing that it's going to be formatted the canonical way. But when modifying code, I have to work with code in one specific format that may not be my preferred format.

Can’t you just set up a linter/formatter to your style, apply it to your style when editing and on save set it to the project style?

It fucks up the diffs in the codebase.

How so? If the canonical format is applied every time you save, you'll always be doing a diff with files using the same format. Of course, it does mean the code in the diffs may not be in your preferred format.

If you want to diff against anything in the past you get a bunch of formatting noise that occludes real changes.

Usually when introducing such a tool you do 1 commit that reformat the whole codebase to the new style and then automatically enforce it.

And in those large reformat commits, add a file like `.git-ignore-revs-file` that is checked in, so you can configure git to ignore that revision and pretend it never existed:

    [blame]
      ignoreRevsFile = ".git-ignore-revs-file"
      markIgnoredLines
      markUnblamableLines

That's an incredibly useful trick to know

This is something that keeps coming back to me either as a feature or as a product of some kind - a tool that can stop this from getting in our way.

The simplest and safest would be to apply the formatter to both the old and the new copy before diffing it. It ceases to be the actual difference at that point, but there are definitely two distinct use cases for diffs - one for humans to read and one for the machine to apply.

The other case that would be amazing but even more of a stretch would be to rewrite the entire history. It seems like there is a spot for "different views of history" and you could do a no-difference merge to join the to histories as of now so that the actual history did not get lost. As I write this, it starts to sound like just a caching system for the idea above.

This needs a highly reliable formatter of course... I have on occasion had code broken when formatting.

If you're talking about moving from a codebase that did not use a consistent formatting style or a style that did not match the auto formatter configuration, sure. I was assuming a case where automatic formatting was done from the start.

Git has an option to ignore certain commits when doing a git blame, —ignore-revs. You can also point it to a file with —ignore-revs-file <file>. You can configure this per project with git config ignoreRevsFile .git-blame-ignore-revs. After doing this, you get nice diffs AND nice looking code. The price to pay is that every developer has to run one git command locally.

I feel like this is a team preference problem and not a formatter problem. The formatter will only do what you tell it, spaces or tabs.

Looking at this another way, formatters are designed to "frustrate" devs into working only 1 way. If you think it's more helpful to have a codebase with mixed spaces/tabs with commits that express each developer's unique flair, then a formatter is not for your team.

Formatters are a way for one person who likes the formatters output to enforce their will on other who might not necessarily like that.