[philsnow]

I don’t think I’ve ever gotten paid for a line of c++ but Google has a “style guide” for internal c++ code that omits something like 3/4 of the language, and people seemed pretty happy with it overall. Maybe not “happy” but “grudgingly accepting because it beats the Wild West alternative”.

[marcosdumay]

C with classes and text-template generics would be an ok subset of the language, if external concepts didn't keep creeping into its semantics. The problem is that they do.

Almost every part of C++ creeps into almost every other part, and C was already complex enough... and let's just ignore that C++ is not completely compatible with C.

[jimbobthrowawy]

Is it really 3/4ths the language? (mostly culled libraries, or features?) I remember reading an old pdf published by the US air force about the subset of c++ features you're allowed to use for contracted software, and it's so different it may as well be a different language.

I think I found it via a stackexchange answer about how the "Wiring" language for Arduino sketches differs from regular c++. In Wiring, it's mostly things like no rtti, no virtual methods not resolvable at compile time, no exceptions, unsafe-math, permissive casting, pre-build system concatenates all .ino files into one .cpp file, very limited libraries, and some default includes.

[vitus]

There are a number of standard libraries that we (Google) ban because we have in-house alternatives that we generally prefer. (In some cases, this is due to compatibility with our threading model. In others, it's probably due to inertia.)

From a skim: <chrono>, <filesystem>, <thread> (along with other concurrency libraries like <mutex> and <future>) are the main ones.

As far as language features that we ban, it's notable that we ban exceptions. Rvalue references are generally discouraged outside of well-trod paths (e.g. move constructors). We ban runtime type information (dynamic_cast, typeid, etc). There are some newer features in C++20 that we haven't accepted yet (modules, ranges, coroutines), due to lack of tooling, concerns about performance, and more.

Sometimes these bans get reversed (there was a long-standing ban on mutable reference parameters that was overturned after many years of discussion).

One of the key points we try to emphasize is that readability is primarily about reading other people's code, and so we provide well-trod paths that try to avoid pitfalls and generally surprising behavior (e.g. this article's focus on initialization? https://abseil.io/tips/88). There is value in moving closer to Python's "There should be one-- and preferably only one --obvious way to do it."

We assert that one of the goals of the style guide (the second section, after Background) is that rules should pull their own weight; we explicitly cite this as a reason why we don't ban goto. I imagine this is also why there isn't an explicit ban on alternative operator representations (e.g. writing `if (foo and bar) <% baz(); %>`).

I don't think I agree that every rule pulls its own weight -- I like to cite that I copy-pasted the internal version of the style guide into a Google doc earlier this year to see how long it was... and it clocked in at over 100 pages. But maybe that's an indicator of how complex C++ is, where we have to make the tradeoff between being concise, being precise, and providing sufficient context.

[fsckboy]

is google's "internal" style guide this?

https://google.github.io/styleguide/cppguide.html

[JasonSage]

Nit: parent didn't call it an internal style guide, but a style guide for their internal C++.

(I'm sure it is.)

[fsckboy]

Nit nit: I don't accept your quibble, I think my usage was well within English usage standards; I even put "internal" in quotes! Consider this hypothetical conversation:

"Is the style guide they use for internal projects the same as this style guide that they have published externally?"

"could you clarify which ones you're talking about?"

"Is the internal style guide you described the same as this one I found in google's account on github?"

"oh, I see what you mean"

will you send your second, or shall we simply pistols-at-dawn?

[kelnos]

I think this is a tough one, and different people are going to interpret it differently.

The fact that you put "internal" in quotes suggested to me a mild level of sarcasm or disbelief, i.e, I read your message as "You mean this style guide, published on the internet, for all to see? Clearly that's not 'internal'!"

Either way, to me, "internal style guide" (regardless of any quotes placed around any word) means "style guide that is internal" (that is, the style guide itself is private or unpublished).

But the person you were replying to called it a "style guide for internal c++ code": that word ordering makes it clear that "internal" is describing "c++ projects", and that the internal/external (or unpublished/published or private/public) status of the style guide itself is not being talked about at all.

(As an aside, if the commenter upthread had instead said "internal style guide for c++ code", that could have also meant the same thing, but would have been ambiguous, as it wouldn't have been clear if "internal" was describing "style guide" or "c++ code", or both, even. But "style guide for internal c++ code" is about as unambiguous as you can get.)

[fsckboy]

you are mistaken how English works, how punctuation works, and how context works wrt parsing and semantics. Freighting what I said with your misinterpretations is on you, not me.

what noun cluster would you use for the style guide that google uses internally? Their internal style guide is perfectly accurate. If they publish it externally, does make it no longer their internal style guide? Nope. Would it make somebody exploring the topic wish to add the clarification "oh, their internal and external style guides are one and the same"? Yes.

None of that conflicts with what I wrote, but it does conflict with what you wrote.

[philsnow]

“External internal style guide” vs “internal external style guide”, both could make sense in different contexts.

Like I said, I never wrote c++ there so I’m quite likely misremembering details, but IIRC the published style guide linked to upthread is more or less a snapshot of the previously-unpublished style guide used internally for internal code. It may have some omissions and it’s quite likely out of date.

I’m just amused that this discussion about semantics reminds me so much of the gif linked from https://news.ycombinator.com/item?id=40882247

[JasonSage]

> you are mistaken how English works, how punctuation works, and how context works wrt parsing and semantics. Freighting what I said with your misinterpretations is on you, not me.

Uhm, no. I think you've got that completely backwards. Agree entirely with what they said, not at all with your interpretation. I think you're flat-out wrong here.

[samatman]

Nit^3: this point would have been effectively conveyed as '"Google's internal style guide"'. By putting only "internal" into quotes, you call into question whether its public existence invalidates the internal nature of it.

Whereas the respondent said this:

> Google has a “style guide” for internal c++ code

This is a style guide for definitely-internal c++ code, with the internality of the style guide itself unspecified. I'm not sure what the effect of the scare quotes around "style guide" is meant to be, just that it doesn't move the internal part next to the style guide part.

Putting the whole thing in quotes, rather than just "internal", questions whether the guide you found is the guide referred to, rather than the internal nature of the style guide itself, which the quoted sentence takes no position on.

This has been your daily dose of Hacker News style guides for discussing style guides.

[Maxatar]

>"Is the style guide they use for internal projects the same as this style guide that they have published externally?"

Consider that the style guide that AirBnB uses for internal projects is not the same as the style guide they publish externally, and you can sympathize with why the distinction matters :P.

[fsckboy]

"the distinction" is literally the question I was asking to clarify, so telling me the distinction matters is divorced from the reality of my comment

[Maxatar]

Yikes! Tough day today?

[vitus]

Yes, modulo some text that's inappropriate to post externally. (Often, because they reference internal libraries in google3 -- this includes things like the ban on <thread> and <future>).