[swift-evolution] [Review] SE-0101: Rename sizeof and related functions to comply with API Guidelines

[John McCall]

> On Jun 30, 2016, at 10:41 PM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:
> On Fri, Jul 1, 2016 at 12:03 AM, Dave Abrahams via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> 
> on Thu Jun 30 2016, John McCall <rjmccall-AT-apple.com> wrote:
> 
> >> On Jun 30, 2016, at 6:12 PM, Dave Abrahams via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> >> on Thu Jun 30 2016, Matthew Johnson <matthew-AT-anandabits.com <http://matthew-at-anandabits.com/ <http://matthew-at-anandabits.com/>>> wrote:
> >>
> >>> Sent from my iPad
> >>>
> >
> >>>> On Jun 30, 2016, at 6:59 PM, Erica Sadun via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> >>>>
> >>>>
> >>>>>> On Jun 30, 2016, at 5:47 PM, James Berry <jberry at rogueorbit.com <mailto:jberry at rogueorbit.com>> wrote:
> >>>>>>
> >>>>>>
> >>>>>> On Jun 30, 2016, at 4:05 PM, Dave Abrahams via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> >>>>>> on Thu Jun 30 2016, Erica Sadun <erica-AT-ericasadun.com> wrote:
> >>>>>>
> >>>>>>>> On Jun 30, 2016, at 4:41 PM, Dave Abrahams <dabrahams at apple.com <mailto:dabrahams at apple.com>> wrote:
> >>>>>>>>> I mentioned this in a comment on the gist already, but I'm really not
> >>>>>>>>> digging the "array" in `arraySpacing`. We've already moved from top-level
> >>>>>>>>> "stride" to "memory layout spacing," gaining plenty of clarity. I'm
> >>>>>>>>> skeptical that the "array" adds anything more. Moreover, it muddies the
> >>>>>>>>> waters by mentioning a specific type (Array) in a context where you're
> >>>>>>>>> querying the memory layout properties of another type.
> >>>>>>>>
> >>>>>>>> OK, I agree with that.  If we have “alignment” rather than
> >>>>>>>> “defaultAlignment,” I suppose we can have plain “spacing.”
> >>>>>>>
> >>>>>>> No way to last-second sell you on interval rather than spacing?
> >>>>>>
> >>>>>> If you can explain why it's better.
> >>>>>>
> >>>>>>> // Returns the least possible interval between distinct instances of
> >>>>>>> /// `T` in memory.  The result is always positive.
> >>>>>>
> >>>>>> For me, “interval” doesn't go with “size” and “alignment,” which are all
> >>>>>> about physical distances and locations.  There are all kinds of
> >>>>>> “intervals,” e.g. time intervals.
> >>>>>
> >>>>> Hmm. Sounds like stride to me. stride or byteStride?
> >>>>>
> >>>>> James
> >>>>
> >>>> FAQ: "Why aren't you using the obvious phrase `stride` for something that clearly
> >>>> returns the memory stride?"
> >>>>
> >>>> ANSWER: "As stride already has a well-established meaning in the standard library,
> >>>> this proposal changes the name to spacing, providing a simple but correct name that
> >>>> works well enough in its intended use. Measuring memory is sufficiently esoteric
> >>>> that we prefer to reserve `stride` for a more common use case."
> >>>
> >>> Counter: some words have more than one well established meaning when
> >>> used in different contexts.  'spacing' isn't too bad here (much better
> >>> than 'arraySpacing') but sticking to the term of art 'stride' would be
> >>> best IMO.  As James mentioned, spacing implies empty space *between*
> >>> items whereas stride matches the meaning of this property *exactly*
> >>> (which is why it is the term of art).
> >>>
> >>> If a programmer can't distinguish between a 'stride' property on
> >>> MemoryLayout and the 'stride' function they probably have no business
> >>> doing anything which requires use of MemoryLayout in the first place.
> >>
> >> I don't believe that “stride” *is* the accepted term of art for this
> >> meaning.  I never heard of the idea of types having an intrinsic
> >> “stride” until I arrived on the Swift project.  That usage came from
> >> “strideof.”
> >>
> >> If you all swear up and down that you've been talking about “the stride
> >> of a type” for more than 2 years, I won't fight you on this.
> >> Otherwise... well, I still won't fight; I'm being crushed by an
> >> avalanche of bikesheds and I can't muster the energy ;->... but I'll
> >> forever be plagued by doubts about the name.
> >
> > As the person who originally picked "stride" here, I agree that I've never
> > heard of people talking about the "stride" of a type; people talk about striding
> > over an array, and they talk about the size of one's stride, and that size
> > can be measured in bytes.  That's all I was thinking.
> >
> > However, I was just picking a name for an internal implementation concept;
> > I did not expect it to be used in the standard library.
> >
> > I don't really like "spacing"; it sounds too much like a synonym for "padding",
> > i.e. the amount of empty space between elements rather than the total amount
> > of space for each element.  But I don't mean to re-open wounds; if people
> > have settled on "spacing", have at it.
> 
> Better names are always welcome if you can come up with one.
> 
> FWIW, courtesy of the thesaurus, curated to eliminate clearly unsuitable words:
> breadth, dimension, expanse, interval, period, space, span, stretch, width
> 
> Of these, span might be the most OK.

Another thought is "arrayElementSize", or "sizeAsArrayElement", or "sizeInArray".  Somewhat verbose, though.

John.
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