I think that this is a good start, but it doesn’t go quite far enough. Part of the problem with a policy that requires people to avoid reformatting of stuff they don’t touch is that it propagates formatting divergence. Sometimes because it’s better to conform to the style immediately adjacent the changed, but more so because it prevents the use of tools that reformat entire files (here, I’m not talking about things like names, but more whitespace conventions).
For whitespace at least, I think that we need to do the following: 1. pick a style I really, really don’t care what this is. I’m thinking that we pick whatever people think that the current style is and give folks a fixed period to debate changes. 2. create some tools These tools should help people conform to the style. Primarily, what is needed is a tool with appropriate configuration that runs on the command line — e.g., mach reformat … clang-format is looking like a good candidate for C/C++, it just needs a configuration. For JavaScript, I’ve used the python js-beautify, but it’s pretty light on configuration options, it might need some hacking to make it better. Ideally though, there should be set of configuration files for common editors. I’m certain there are plenty out there already. Let’s bring them all together (attaching the files https://developer.mozilla.org/en-US/docs/Developer_Guide/Coding_Style might be enough). 3. reformat everything Take the command line tool and run it over all the code. I realise that this is the contentious part, but you don’t get the real benefits until you do this. Once you do this, it’s safe to reformat files at any time without messing with parts of files that you haven’t touched. This is important because many tools only reformat entire files. As for `hg blame` and related tools, I have a workaround for that. I’ve knocked together a tool that takes a file and a reformatter command line, and churns out a series of patches that retain blame: https://github.com/martinthomson/blame-bridge The patch bitrot problem is not easy to work around, but that will depend on how closely the affected files already conformed to the style guide. 4. enforce compliance This is probably a step for the future, but if there was - for example - a commit bot that waited for a clean build+test run, adding a format check to that run would allow the bot to block patches that screwed up the formatting of files. —Martin On 2014-01-05, at 18:34, Nicholas Nethercote <n.netherc...@gmail.com> wrote: > We've had some recent discussions about code style. I have a propasal > > For the purpose of this proposal I will assume that there is consensus on the > following ideas. > > - Having multiple code styles is bad. > > - Therefore, reducing the number of code styles in our code is a win (though > there are some caveats relating to how we get to that state, which I discuss > below). > > - The standard Mozilla style is good enough. (It's not perfect, and it should > continue to evolve, but if you have any pet peeves please mention them in a > different thread to this one.) > > With these ideas in mind, a goal is clear: convert non-Mozilla-style code to > Mozilla-style code, within reason. > > There are two notions that block this goal. > > - Our rule of thumb is to follow existing style in a file. From the style > guide: > > "The following norms should be followed for new code, and for Tower of Babel > code that needs cleanup. For existing code, use the prevailing style in a > file or module, or ask the owner if you are on someone else's turf and it's > not clear what style to use." > > This implies that large-scale changes to convert existing code to standard > style are discouraged. (I'd be interested to hear if people think this > implication is incorrect, though in my experience it is not.) > > I propose that we officially remove this implicit discouragement, and even > encourage changes that convert non-Mozilla-style code to Mozilla-style (with > some exceptions; see below). When modifying badly-styled code, following > existing style is still probably best. > > However, large-scale style fixes have the following downsides. > > - They complicate |hg blame|, but plenty of existing refactorings (e.g. > removing old types) have done likewise, and these are bearable if they > aren't too common. Therefore, style conversions should do entire files in > a single patch, where possible, and such patches should not make any > non-style changes. (However, to ease reviewing, it might be worth > putting fixes to separate style problems in separate patches. E.g. all > indentation fixes could be in one patch, separate from other changes. > These would be combined before landing. See bug 956199 for an example.) > > - They can bitrot patches. This is hard to avoid. > > However, I imagine changes would happen in a piecemeal fashion, e.g. one > module or directory at a time, or even one file at a time. (Again, see bug > 956199 for an example.) A gigantic change-all-the-code patch seems > unrealistic. > > - There is an semi-official policy that the owner of a module can dictate its > style. Examples: SpiderMonkey, Storage, MFBT. > > There appears to be no good reason for this and I propose we remove it. > Possibly with the exception of SpiderMonkey (and XPConnect?), due to it being > an old and large module with its own well-established style. > > Also, we probably shouldn't change the style of imported third-party code; > even if we aren't tracking upstream, we might still want to trade patches. > (Indeed, it might even be worth having some kind of marking at the top of > files to indicate this, a bit like a modeline?) > > Finally, this is a proposal only to reduce the number of styles in our > codebase. There are other ideas floating around, such as using automated tools > to enforce consistency, but I consider them orthogonal to or > follow-ups/refinements of this proposal -- nothing can happen unless we agree > on a direction (fewer styles!) and a way to move in that direction > (non-trivial > style changes are ok!) > > Nick > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
