[llvm-dev] RFC: changing variable naming rules in LLVM codebase (original) (raw)

Chandler Carruth via llvm-dev llvm-dev at lists.llvm.org
Mon Feb 18 18:08:22 PST 2019

On Mon, Feb 18, 2019 at 10:10 AM Krzysztof Parzyszek via llvm-dev < llvm-dev at lists.llvm.org> wrote:

On 2/18/2019 4:15 AM, Michael Platings via llvm-dev wrote: > Taking my previous example [1]: > > InnerLoopVectorizer LB(L, PSE, LI, DT, TLI, TTI, AC, ORE, VF.Width, IC, > &LVL, &CM); > > If we imagine that over time it evolves such that 50% of the variables have been renamed to camelBack versions of the type names, then it will look like this: > > InnerLoopVectorizer LB(loop, PSE, loopInfo, DT, targetLibraryInfo, TTI, > assumptionCache, ORE, vectorizationFactor.Width, IC, > &loopVectorizationLegality, &CM);

Hold on... The change from UpperCamel to lowerCamel should be separate from going from X to somethingOtherName.

FWIW, I suspect separating the transition of our acronyms from the transition of identifiers with non-acronym words may be an effective way to chip away at the transition cost... Definitely an area that people who really care about this should look at carefully.

It seems like in this example, TLI is changed to targetLibraryInfo for the purpose of having a name that lowerCamel can be applied to, which is, at best, backwards. When a new person sees "TLI", they won't know what it is. When an LLVM developer sees "TLI" they know exactly what it is, even without any context. At the same time, a person is new to LLVM for only a certain period of time, much shorter than the lifetime of the code. The key to readability is to make the important things easy to see, and get the unimportant things out of the way. By using completely expanded names we run the risk of making everything equally "easy to see"...

I think this bias towards acronyms (which I used to share) due to keeping things short but still recognizable once people become deeply familiar with LLVM is the wrong prioritization. It does work well for experienced LLVM developers, but I think we should do much more to facilitate and encourage people who are not in this set. While this does come at some cost to highly experienced LLVM developers (reading library_info instead of TLI), but it seems easily worth it to make the codebase more accessible to new contributors. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190218/8d82b5ef/attachment.html>

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