Let's say I have a state variable s.
I've got a .z.ws hook that responds to websocket messages and runs:
.z.ws: {handleMsg x}
Do I have to declare s as global for handleMsg to be able to update s?
Ideally, what I'd want is something like:
s: handleMsg[s;x]
where handleMsg is a pure function (it doesn't affect any globals on the inside).
Should I declare s as global and then try to do this assignment inside the websocket callback?
You don't pre-declare variables as global in kdb, they're global if you make them global at any point (and if you reference them as a global).
q)func:{x+1}
/s is local and treated as such
q){s:func[1]}[]
2
/it is not a global
q)s
's
/this would make it global
q){`s set func[1]}[]
`s
/or
q){s::func[1]}[]
/now it's global
q)s
2
/but a local of the same name would take preference
q){s:func[100];s}[]
101
q)s
2
/you can force-reference the global if required
q){s:func[100];value `s}[]
2
So you're in complete control over what's global, what isn't, when you're referencing a local and when you're referencing a global.