?. equivalent for accessing lists

ID:2411099
 
Nov 14 2018, 8:31 am
Resolved
List access now has a ?[] operator. If the list is null, the list access will do nothing and fail without an error.
Applies to:DM Language
Status: Resolved (514.1543)
This issue has been resolved.
// imagine having a list that your code accesses heavily...
// but there's no guarantee said list is always initialized.
mob/var/somelist[]

// currently, everywhere you access the list has to be written as:
somelist && somelist[index]

// my suggestion would shorten this to:
somelist?[index]


...Normally I'd create a proc for the sake of sanity checking, but that becomes non-viable when you have many frequently used lists. For now I've resorted to always having the lists initialized, but I figured I'd toss this suggestion out there.
Nov 14 2018, 8:00 pm
+

var/i
if(somelist && (i = somelist[index]))


is a pattern I type pretty much constantly.
Nov 14 2018, 11:30 pm
Also +1 from me, I pretty much do exactly what Ter does all over the place.
Nov 16 2018, 8:49 am
. already works for lists, like so:
var/list/foo = list("bar")
world.log << foo.[1]


this prints out "bar"

?. is however an error:

expected var or proc name after ?. operator
Dec 2 2018, 3:18 pm
I'd have liked to have this frequently in the past
Jun 12 2019, 7:04 am
Bump.
Jun 12 2019, 9:03 am
Aye
Jul 10 2019, 8:25 am
Bumping this again because I was reminded by some code that I still want this. ?. has been shown to be a micro optimization in some places which is nice in the very hot code. A similar functionality for lists would allow me to slightly speed up some code like the following

if(somelist && somelist[key])
  dostuff

to
if(somelist?[key])
  dostuff
Jul 10 2019, 12:32 pm
It's not on the list for 513 but I'm open to it for 514.
Jun 16 2020, 2:42 pm
This is implemented in 514 and will be closed once the first beta is released.
Feb 1 2021, 9:50 am
Lummox JR resolved issue with message:
List access now has a ?[] operator. If the list is null, the list access will do nothing and fail without an error.