On Friday, 10 November 2017 at 05:23:53 UTC, Adam Wilson wrote:
On 11/6/17 12:20, Michael wrote:
I can't quite see why this proposal is such a big deal to
people - as
has been restated, it's just a quick change in the parser for
a slight
contraction in the code, and nothing language-breaking, it's
not a big
change to the language at all.
On Monday, 6 November 2017 at 19:13:59 UTC, Adam Wilson wrote:
I am all for the Elvis operator, however I have two
reservations about
it. The first is that I don't see much use for it without a
null-conditional. The second is that the current proposed
syntax ?: is
MUCH to easily confused with ?.
This is not easy to read: obj1?.obj2?.prop3?:constant.
When designing syntax sugar, ergonomics are very important,
otherwise
people won't use it. Microsoft spent a LOT of time and
treasure to
learn these lessons for us. I see no reason to ignore them
just
because "we don't like Microsoft"
My proposal would be to copy what MSFT did, expect that I
would I
would introduce both operators at the same time.
Syntax as follows: obj1?.obj2?.prop3 ?? constant
In practice I don't see much use of the idiom outside of
null's. The
ONLY other thing that would work there is a boolean field and
you
might as well just return the boolean itself because the
return values
have to match types.
I feel this is kind of embellished somewhat. When you write
This is not easy to read: obj1?.obj2?.prop3?:constant.
you're not separating it out as you do when you write your
preferred
version:
Syntax as follows: obj1?.obj2?.prop3 ?? constant
How is
obj1?.obj2?.prop3 ?: constant
not as easy to read as
obj1?.obj2?.prop3 ?? constant
You're right, I didn't, that was intentional, because sometimes
people write things like that. And it took a while for anyone
to say anything about it. That is my point.
But that's the thing. The ?? is significantly more obvious in
the condensed version.
This is something that a UX designer would recognize instantly,
but human factors are very definitely not our strong skill as
engineers. FWIW, my human factors experience comes from the
deep study of airline crashes that I do as a pilot.
to me they are the same in terms of readability, only with ??
you have
greater chances of mistyping and adding a second ? in there
somewhere,
whereas the ?: is just a contraction of the current syntax, I
really
don't think it's that difficult, so I'm not sure what people's
hang-ups
are, but I don't think the argument that ?? is easier to read
than ?:
holds any weight here, because one *is* a change to the
language, and
the other is a change to the parser and a contraction of a
standard
convention.
Two things. ?: is ALSO a change a to language (lexer+parser).
As to the whole "it's no more likely to typo the colon than the
question" argument, sure, but that depends on the keyboard
layout more than anything else, what works for you may not work
elsewhere. And in either case, it's an easy compiler error. So
you don't win anything with the ?:, but you win readability
with the ??. MSFT spends a LOT of time studying these things.
It would be wise to learn for free from the money they spent.
I still dont get your point. Are you sure `??` isn't more
readable for you, because you are just used to it?
I think `?:` makes more sense to me and people who learn the D
programming language.
At least As log as `null` becomes `false` and non-null-pointer
becomes `true`.
If the operator shall check for `null` only, I would be fine with
`??`.
Because then it wouldn't be a true shortcut of
https://dlang.org/spec/expression.html#ConditionalExpression
anymore
I wonder what Mr. Bright and Mr. Alexandrescu would say about the
request to implement both, `??` and `?:`.
