You could file an issue there, where it's more likely to get seen by interested parties. The basic concept is basically reversed augmented assignment, where `a @= b` usually means `a = a @ b`, you'd want something like `a =@ b` meaning `a = b @ a`. (Operator is up for debate, and `=-` conflicts with negation.)
I could see the use of it - `??` is the most common case for me, but a reverse subtraction or easy reciprocal division would also be convenient in some cases. I'm neutral on the idea, though. ----- Isiah Meadows [email protected] www.isiahmeadows.com On Thu, Jul 5, 2018 at 4:53 PM, Jacob Pratt <[email protected]> wrote: > This idea isn't quite the same as ||=, as that includes any falsey value, > nor ??=, as that includes null. My thought was to be able to set a property > if there is a value that exists (which would include null, but not > undefined). > > It's certainly similar — should this be considered for addition to that > existing proposal? > > My thinking was along the lines of "Set this if there is something to set. > If not, just keep going". It can be done with an if statement, but would > require a temporary reference due to getters and/or method calls. > > jhpratt > > On Thu, Jul 5, 2018 at 3:08 AM, Isiah Meadows <[email protected]> > wrote: >> >> How about you all take a look here: >> https://github.com/tc39/proposal-logical-assignment >> >> Originally, it was at >> <https://github.com/tc39/proposal-nullish-coalescing>, but here >> <https://github.com/tc39/proposal-nullish-coalescing/issues/1>, it was >> discussed and pushed off to the logical assignment proposal as it was >> also a short-circuiting operator, even though it wasn't really a >> *boolean* operator. >> >> ----- >> >> Isiah Meadows >> [email protected] >> www.isiahmeadows.com >> >> >> On Wed, Jul 4, 2018 at 10:25 PM, Sam Ruby <[email protected]> wrote: >> > On Wed, Jul 4, 2018 at 7:12 PM, Jacob Pratt <[email protected]> >> > wrote: >> >> I've been having this thought recently, after running across a >> >> potential use >> >> case in practice. There will likely be conditional accessors at some >> >> point >> >> in the future (with optional chaining), but there will not be >> >> conditional >> >> assignment. >> >> >> >> My thought was to have the following: >> >> this.foo ?= params?.foo; >> >> which can be desugared to >> >> if (($ref = params?.foo) !== undefined) { this.foo = $ref; } >> >> >> >> I would strictly check for undefined, rather than nullish, as anything >> >> other >> >> than undefined would indicate that a value is present that can be set. >> >> If no >> >> value is present (such as a missing key on an object), nothing would be >> >> set. >> >> A reference must be used for the general case, as the object being >> >> assigned >> >> (the RHS) could be a function or getter with side-effects. >> >> >> >> Not sure if it should be ?= or =?, as it would look somewhat odd (IMO) >> >> for >> >> things like ?+= or +=?. >> >> >> >> Initial thoughts? >> > >> > Perl and Ruby have "||=" and "&&=" operators. They don't strictly >> > check for undefined in either language. >> > >> > These operators are frequently used (in particular, "||="). I do miss >> > them. >> > >> > Looking at the node.js source: >> > >> > $ find . -name '*.js' -type f | xargs egrep ' (\S+) = \1 \|\| ' | wc -l >> > 1416 >> > >> > $ find . -name '*.js' -type f | xargs egrep ' if \(!(\S+)\) \1 = ' | wc >> > -l >> > 497 >> > >> > Nearly 2K occurrences in one code base. >> > >> >> Jacob Pratt >> > >> > - Sam Ruby >> > _______________________________________________ >> > es-discuss mailing list >> > [email protected] >> > https://mail.mozilla.org/listinfo/es-discuss > > _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
