[pretty] Add example sources to pretty.

[turon]

Problem

Examples are only getting style formatted via restyled during pull request right now.

Solution

This PR adds the examples sources to PRETTY_FILES so they can be checked and formatted locally during development ahead of submitting a pull request.

Helps resolve friction cited in #345.

[woody-apple]

@turon First time I'm digging into pretty, so sorry for the dumb question... is there a way to make this such that every developer doesn't have to remember to do this for every file added? (Re-inforces why I prefer restyled).

Maybe we can use restyled.io locally instead of make pretty? @rwalker-apple thoughts? That way we have stuff that's at least inline, and doesn't require this manual addition of stuff...

[turon]

@woody-apple I'm a big proponent of simplifying the developer experience and resonate with the goals you mention; unfortunately, I don't know of a simpler way to do it with autotools.

[woody-apple]

@turon would you be against me moving make pretty to run this? https://github.com/restyled-io/restyler

It does exactly what our repository is doing.

[turon]

@woody-apple I don't have a problem with it. @gerickson?

[gerickson]

@woody-apple I don't have a problem with it. @gerickson?

As long as it can run offline and doesn't explicitly require a Docker container.

[woody-apple]

@gerickson Why is offline and docker required for active development?

Trying to understand the resistance here to matching to what the repository does? Seems like a benefit to use a general system that we've deployed here rather than one that requires each developer to understand which file to edit to make sure make-pretty works.

Note: You only need to grab the container once with Docker, so technically doesn't require online.

[gerickson]

In terms of offline, I'd like to ensure that, as a developer, if I happen to be on a plane or somewhere where I can't consistently ping out to remote services that I can do everything I need to do to land commits locally where the push to remote is a final step I take when I land or get connectivity back. If style compliance is part of landing commits locally with confidence that I've passed all quality gates, then the tooling to do that should be local.

I may not understand restyled.io well at this point; however, my understanding is that the service is running remote tooling to do what clang-format formerly did locally. But, like travis-ci and others, it may just be triggering clang-format.

[woody-apple]

restyled.io just uses clang-format, does exactly the same thing that make-pretty tries to do, but does so globally on files rather than using a developer supplied list of files to make-pretty. It also uses shell check for others, as well as markdown cleanup using 'pretty-markdown'.

I agree we need the tooling to work on the developer's machine & it's true that you need to download the docker image once, but then it's offline forever. That doesn't seem like a burden personally. Same goes for builds & VSCode development now, if you want builds to run like travis, you need to download the container once, and then you're good to go.

[rwalker-apple]

a "format entire tree" as a script in integrations/ would be my preference, but is a low priority given how awesome restyled has been so far

[woody-apple]

Handling the prettifying of the tree here: #432

Another PR to come later with some changes to make this easy for anyone to run.

[woody-apple]

@jelderton @BroderickCarlin ?