[llvm-dev] changing variable naming rules in LLVM codebase

Zachary Turner via llvm-dev llvm-dev at lists.llvm.org
Thu Feb 14 08:02:47 PST 2019

fwiw, LLDB also uses m_ for member variables, so if we were to adopt an m
prefix, then in conjunction with lowercase_underscore the entire codebase
would be conforming.

On Thu, Feb 14, 2019 at 5:02 AM Nemanja Ivanovic <nemanja.i.ibm at gmail.com>

> I have to agree with Paul that I think it is rather useful to have a
> naming convention that distinguishes class members from locals, etc. I'm
> not sure what that would look like, whether an m prefix for data members
> would be something others would entertain, but something that makes it
> clear would probably be useful. To use Paul's example, I think that
> mTheStuff vs. TheStuff makes it super easy to visually identify what this
> is. I imagine this wasn't mentioned in this thread or previously adopted
> because of some good reason I am not aware of.
> A more minor point about underscores vs camel case - what I like about
> camel case is that it generally keeps my fingers on the 3 rows of the
> keyboard I use the most. From an ergonomics perspective, I find typing a
> whole lot of underscores a bit unnatural. So since I find camel case easier
> to type and equally as readable, I would favour it over underscores.
> On Wed, Feb 13, 2019 at 11:03 PM James Y Knight via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>> There is of course some amount of llvm and clang code which already uses
>> initialLowerCaseNames for variable names too, contrary to the style guide.
>> I don't know how to easily quantify how much.
>> E.g. ParseGNUAttributes in clang/include/clang/Parse/Parser.h is one I
>> noticed.
>> On Wed, Feb 13, 2019 at 2:49 PM Zachary Turner via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>> I want to reiterate the benefit that underscore_names would bring.  To
>>> be clear it's not my favorite style, but it does have a very concrete
>>> advantage which is that we have a very large subproject already using it.
>>> it doesn't make sense to do a purely aesthetic move that not everyone is
>>> going to agree on anyway, when we could do one with actual tangible value.
>>> On Wed, Feb 13, 2019 at 8:52 AM <paul.robinson at sony.com> wrote:
>>>> Chandler wrote:
>>>> > FWIW, I'm pretty strongly opposed to humbleCamelCase. We already use
>>>> that
>>>> > style so something else.
>>>> Presumably you are equally opposed to RegularCamelCase, because we
>>>> already
>>>> use *that* style for something else.
>>>> But really, objecting on the grounds that a given style is already used
>>>> for
>>>> function names is really a very weak argument.  IME function names are
>>>> *incredibly* *hard* to confuse with anything else, because they
>>>> *always* have
>>>> surrounding syntactic context. Given `TheStuff->fooBar().getThingy()`
>>>> is it
>>>> even conceivable that you might not instantly get that fooBar and
>>>> getThingy
>>>> are methods?  Therefore, using the same convention for some other kind
>>>> of
>>>> name is Not Confusing.
>>>> OTOH, `TheStuff` comes out of nowhere with no clues to its origin, and
>>>> *that*
>>>> is a barrier to code-reading IME.  Even renaming it to `stuff` would
>>>> help
>>>> approximately zero percent. Parameter? Local? Class member? Global?
>>>> LLVM has
>>>> incredibly few globals for other reasons, but using the same convention
>>>> for
>>>> locals and class members is a real problem for code-reading, especially
>>>> code
>>>> operating in methods for classes you're not super familiar with.
>>>> I acknowledge that the current RFC doesn't propose a member naming
>>>> convention
>>>> different from other variables, but IMO it really ought to.  *That* is
>>>> the
>>>> distinction that would really help in reading unfamiliar code.
>>>> --paulr
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