[swift-evolution] Trial balloon: conforming sizeof, sizeofValue, etc. to naming guidelines

[Dave Abrahams]

on Mon May 02 2016, Xiaodi Wu <swift-evolution at swift.org> wrote:

> I like it, but how do you accommodate sizeofValue, etc?

IMO you don't.  I added those years ago on a whim, when whims were what
we had to guide development.  I'm unconvinced they add value to Swift.

>
>
> On Mon, May 2, 2016 at 11:46 Dave Abrahams
> <dabrahams at apple.com> wrote:
>
>     on Sun May 01 2016, Xiaodi Wu <xiaodi.wu-AT-gmail.com> wrote:
>
>     > It's a bad habit of mine, I guess, to err on the side of suggesting
>     conservative
>     > changes on the assumption that it'll be maximally acceptable. If there's
>     > appetite for a more serious renaming, and as you say these are considered
>     > relatively rarely used, then it's a world of possibility!
>     >
>     > We could do as Shawn suggested and follow precedent in some other
>     languages by
>     > moving these functions out of the global scope. Perhaps these will meet
>     with
>     > some satisfaction:
>     >
>     > ```
>     > Memory.footprint(of:)
>     > Memory.alignment(of:)
>     > Memory.spacing(of:)
>     > ```
>
>     I'd rather have
>
>     MemoryLayout<T>.size
>     MemoryLayout<T>.alignment
>     MemoryLayout<T>.spacing
>
>     -Dave
>
>     > On Sun, May 1, 2016 at 21:41 Dave Abrahams via swift-evolution
>     > <swift-evolution at swift.org> wrote:
>     >
>     > on Sun May 01 2016, Xiaodi Wu
>     <swift-evolution at swift.org> wrote:
>     >
>     > > On Sun, May 1, 2016 at 7:00 PM, Dave Abrahams via swift-evolution
>     > > <swift-evolution at swift.org> wrote:
>     > >
>     > > on Thu Apr 28 2016, Xiaodi Wu
>     > > <swift-evolution at swift.org> wrote:
>     > >
>     > > > We all know and love sizeof(), but given that it's different from its
>     C
>     > > > counterpart anyway, shouldn't these conform to Swift naming
>     guidelines?
>     > In
>     > > other
>     > > > words, after SE-0006, shouldn't these names be as follows?
>     > > >
>     > > > ```
>     > > > size<T>(of: T.Type)
>     > > > size<T>(ofValue: T)
>     > > > stride<T>(of: T.Type)
>     > > > stride<T>(ofValue: T)
>     > > > align<T>(of: T.Type)
>     > > > align<T>(ofValue: T)
>     > > > ```
>     > > >
>     > > > There are obvious issues with two different things named `stride`, but
>     > IMO
>     > > > that's best addressed by renaming one of them; the real problem is
>     that
>     > > the word
>     > > > stride is used in two different ways already. Thoughts?
>     > >
>     > > These functions correspond to C and LLVM primitives and we consciously
>     > > kept those names because they are terms of art.
>     > >
>     > > I recognize that this was the intention behind preserving the names
>     as-is.
>     > The
>     > > thought process behind proposing a renaming was as follows:
>     > >
>     > > * The Swift counterpart to C `sizeof()` is `strideof(_:)`. Thus,
>     although
>     > the
>     > > *names* are treated as terms of art, not all of them are used to mean
>     the
>     > art
>     > > for which they are terms (if you will).
>     >
>     > The specific meaning of sizeof in Swift comes from either LLVM or from
>     > SIL, IIRC. It predates me, but it's supposed to correspond to what the
>     > IRGen level of the compiler calls “sizeof.”
>     >
>     > > To reinforce the separation between C primitives and these Swift
>     > > functions, C `offsetof()` has no Swift counterpart.
>     >
>     > Yes, that's part of the reason I'd very much like to choose more
>     > descriptive names if we are going to move away from the current
>     > spellings. moving the parenthesis is a pretty weak cue that this thing
>     > might be slightly different.
>     >
>     > > * A survey of other languages suggests that, as terms of art, these
>     names
>     > are
>     > > not always treated as a single word but as a phrase, by which I mean
>     that
>     > the
>     > > preposition "of" can be subject to language-specific naming conventions.
>     > For
>     > > example, in Rust you have `size_of()`, `size_of_val()`, etc.; in the .
>     NET
>     > > Framework, you have the `Marshal.SizeOf()` method; and even in LLVM you
>     > > apparently have (and this is based just on googling--my level of
>     > familiarity
>     > > with LLVM is low to nonexistent) struct `AlignOf<T>`.
>     > >
>     > > I don't know that
>     > >
>     > > size(of: T.self)
>     > >
>     > > is particularly descriptive usage, and if we were going to change them
>     > > so they didn't look like sizeof, strideof, alignof I'd want to make them
>     > > far more descriptive. E.g.
>     > >
>     > > memoryFootprint(Int.self)
>     > >
>     > > or
>     > >
>     > > bytesRequiredForStorage(Int.self)
>     > > standardByteAlignment(Int.self)
>     > > bytesBetweenArrayElements(Int.self)
>     > >
>     > > etc.
>     > >
>     > > To my mind, `size(of:)` is not moving away from using a term of art but
>     > rather
>     > > following existing precedent in conforming use of the preposition to
>     > > language-specific conventions.
>     >
>     > The same argument could be made for “mapped” and “reduced.”
>     >
>     > > Like you, I would be hesitant to suggest moving away from these terms
>     > > of art altogether.
>     >
>     > You misunderstand me. I'm not hesitant about that at all. What I
>     > dislike is the idea of being close-to-but-not-quite-the-same as the
>     > source terms to which they correspond. The original terms are not
>     > great, and these facilities are seldom used. They can afford to be
>     > longer and more descriptive.
>     >
>     > > I do think, though, that moving the preposition has the bonus of
>     > > visually suggesting however subtly that `size(of:) ` might have a
>     > > Swift-specific twist that makes it not a drop-in equivalent for C
>     > > `sizeof()`.
>     >
>     > I don't think subtlety is a virtue in this case.
>     >
>     > --
>     > Dave
>     >
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>     >
>
>     --
>     Dave
>
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-- 
Dave