On 4/26/18 11:29 AM, Vern Paxson wrote:
> Just one more thing still: I'm actually
feeling pretty strongly
> against having multiple different operators for the same operation
> (set union, set addition/removal).
I'm maybe convincing myself that it's at least not that useful or
there's alternative ways forward that don't introduce redundancies.
I'm fine with removing "add" and
"delete" for sets! (But seems we gotta
keep them for a good while for backward compatibility. Plus, what would
be the remove operator for tables? "t -= index" seems pretty weird to me.)
A nice thing about "add" and "delete" for sets is that you can infer
data type that you're operating on just looking at the local code/line.
E.g. say you come back to some code after a few months and see "foo +=
1". Not obvious what 'foo' is anymore. Could be vector, set, or count,
But I don't think we should forego '+'
and '-' for sets. It would be too
weird that "v += e" works but "s += e" does not (and "add
v[e]" blows, so
let's not consider going down that path :-P).
Yeah, I agree with that sentiment (on the condition that we did add +/-
I do also notice that you had "s + e" in the proposal and not "v + e".
Isn't that weird by the same logic or is it just an accidental omission?
Once we have s += e, we
certainly should have s -= e. And once we have "s + e", "s1 + s2"
very natural to me too; I don't relish having to explain "oh *that*
work, you have to use s1 | s2" :-P.
That also makes sense, though it's worth seeing what a minimal proposal
looks like without the contentious '+' operations:
s1 - s2, s1 -= s2 Set difference
s1 | s2, s1 |= s2 Set union
s1 & s2, s1 &= s2 Set intersection
s1 ^ s2, s1 ^= s2 Set symmetric difference
c1 | c2, c1 |= c2 Bitwise-or 'count' values
c1 & c2, c1 &= c2 Bitwise-and 'count' values
c1 ^ c2, c1 ^= c2 Bitwise-xor 'count' values
The only one now missing that I'd probably find myself using is:
v += e Append element to vector
And for that, a BiF or generic script-layer function call (if that were
possible) would even make me happy:
That also could go back to what I was saying before about readability:
it would then be more obvious than "v += e" regarding what data types
Same idea would apply to "s += v" and "s -= v" (if we were inclined):
Could that all be an alternative way forward? Or is it missing other