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

[Jacob Bandes-Storch]

There seems to be agreement that "stride" is sensical term for the distance
between values in memory, but it seems like what MemoryLayout wants to
expose is the *minimum* possible stride for a particular type. How do folks
feel about "*minimumStride*"?

On Thu, Jun 30, 2016 at 10:46 PM, James Berry via swift-evolution <
swift-evolution at swift.org> wrote:

>
> > On Jun 30, 2016, at 10:07 PM, Dave Abrahams <dabrahams at apple.com> wrote:
> >
> >
> > on Thu Jun 30 2016, Matthew Johnson <matthew-AT-anandabits.com> wrote:
> >
> >>> On Jun 30, 2016, at 8:12 PM, Dave Abrahams <dabrahams at apple.com>
> wrote:
> >>>
> >>>
> >>> on Thu Jun 30 2016, Matthew Johnson <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> wrote:
> >>>>>
> >>>>>
> >>>>>>> On Jun 30, 2016, at 5:47 PM, James Berry <jberry at rogueorbit.com>
> wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>> On Jun 30, 2016, at 4:05 PM, Dave Abrahams via swift-evolution <
> 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>
> 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.
> >>
> >> I was just throwing in my 2 cents and planned to leave it at that.
> >> The primary reason I chimed in is because I didn’t find the rationale
> >> in the “answer” compelling.  This isn’t something I feel like bike
> >> shedding any further over either.
> >>
> >> https://en.wikipedia.org/wiki/Stride_of_an_array
> >>
> >> Maybe stride isn’t as common as I thought it was (if it was I’m sure
> >> you would have heard of it before Swift) but it certainly predates
> >> Swift in usage.
> >
> > But that's actually a different meaning altogether.  Two “arrays” of
> > type T can have different strides.  They're talking about taking a view
> > onto an underlying series of contiguous Ts that (potentially) skips over
> > elements.
>
> Maybe I come from an esoteric part of the universe. While I’ve never heard
> of stride applied to a type, in particular, the concept of stride as I know
> it applies to any item as laid out in memory, and seems to me to apply
> equally well to any “object” in the loosest form of the word. I believe my
> first experience with it, some 30 years ago, dealt with the row stride in a
> frame buffer or bitmap. This meaning is similar to the array reference as
> above. I disagree that they’re not in that article above talking primarily
> about the same thing that we are: their very first example, under the
> “Padding” headline, seems to exactly match our intent. Their additional
> examples are just hacks/extensions of this concept.
>
> If we were talking about waveforms we’d be talking about period. Stride
> indicates the same thing with regard to items in memory: how long a step do
> you need to take to get from the start of one item to the start of the
> next. So we could use “period”, or “interval”, or “step”, or something. I’m
> just arguing that the most recognizable word to describe this concept, as
> applied to any sort of item in memory, is stride. But again, maybe that’s
> just based on my own experience.
>
> Ultimately, I’m sure it’s not a big deal. I agree with Mathew that people
> using MemoryLayout aren’t likely to confuse the two uses within swift. It’s
> just that if I had to describe the concept we’re describing in
> MemoryLayout, stride would be my first choice, as it seems most apt. Short
> of that, I’m sure that I could read comments and ultimately figure out that
> “interval,” or “spacing,” or whatever, really means “stride” ;)
>
> James
>
>
>
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