[foreign-memaccess] RFR 8231402: layout API implementation is not constant enough

[John Rose]

On Sep 24, 2019, at 12:56 PM, Maurizio Cimadamore <maurizio.cimadamore at oracle.com> wrote:
> 
>> The view factories seem to have a naming inconsistency; there is `asPinned` and `asReadonly`, but `slice`.  Given the slightly odd treatment of views when it comes to temporal bounds, I would prefer the asXxx (which suggests you're going to use the view in place of the original) form, and suggest `asSlice` or `asNarrowed`.
> Good point - yes, the slice is a view and all views should use uniform naming.

Not to go crazy at the bike shed, but it seems to me that spatially narrowed views are
special enough to merit their own intuitive terminology, in the same way that
List has just subList and not asSubList/asSlice.  After all, the contiguous ordering
of a segment of memory is probably its most salient property, and so slicing
is one of the most fundamental operations.  The access modes (tweaked by
asReadOnly) and the temporal properties (tweaked by a scope API and/or
view operations like asPinned) are less salient and don’t deserve special
terms.  (List has very limited view-constructors, but omitting subList is hard
to imagine.)

Also, unlike most view creation operation, the slice creation API has two
degrees of freedom, and they vary over the whole datum being sliced.
Most view creators (think Array.asList) re-interpret the *whole* datum
with minimal configuration parameters.  The effect of this can be seen
by imagining the bikeshed color "asSubSegment” ("asSubSequence”,
etc., as appropriate).  How does that sound?  It sounds wrong IMO,
because the “as” part sets you up to look for a view, but then the “sub”
part doesn’t parse, since no “foo” is alias-able to a “sub-foo” of itself.
(The whole is greater than the part; Cantor’s pairing constructions, etc.)
So a sub-foo is a little like an alias of a foo, but only *part* of a foo.
Calling the sub-foo a “view” of a foo drops the most important fact,
the part/whole distinction.

So, my only objection to “slice” might be that it sounds like a verb where a
noun is probably preferable (but it’s a noun also, which is why I don’t find
it too difficult).  I think a bikeshed color like “subSegment” or “makeSlice”
is a better alternative to “slice” than “asSlice”.

I promise to put away my spray paint now.

— John