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

Dave Abrahams dabrahams at apple.com
Thu Jun 30 20:12:50 CDT 2016

on Thu Jun 30 2016, Matthew Johnson <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

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.


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