types.Table.__update

Method on every table

(table|class).__update(other: table|instance|class, ...): any

Copies every slot from each argument into the table, in place, later arguments overriding earlier ones.

The binding carries no declaration string, so the VM cannot report parameter names. The names above are from this page; the types and attributes still come from the VM. The VM also cannot tell an optional parameter from a variadic tail here, so read the brackets and any trailing ... from the prose below, not from the signature.

Parameters

`other`	table\|instance\|class	a table, class or instance to copy slots from; repeatable, so more than one may be given
`...`	any	repeats

Return value

The table itself.

Errors

Throws Cannot modify immutable object when the table was frozen with freeze().

Throws a type error when an argument is not a table, class or instance, but the wording depends on which one: a bad first other throws parameter 1 of '__update' has an invalid type '...' ; expected: 'table|class|instance', while a bad second or later argument throws parameter N of '<unknown>' has an invalid type '...' ; expected: 'table|class|instance', with N counting the table itself as parameter 1. Only the first argument goes through the VM's own automatic type check, which knows the function's name; the rest are checked by hand inside __update, which does not pass a name along.

Notes

Takes 1 or more arguments - this method is variadic, unlike reduce or findvalue on this page, where a negative arity in the binding does not mean open-ended. t.__update() with no arguments throws a wrong-number-of-parameters error; t.__update(a, b, c) copies a, then b, then c, each overwriting slots the previous ones set.

Despite the name, this is an ordinary method - there is no operator or assignment syntax that calls it implicitly, script code always writes t.__update(other) out. See __merge for the non-mutating version that builds a new table instead of writing into t.

Example

examples/types/table/__update.nut

let t = {fizz=1}
let r = t.__update({buzz=2}, {fizz=10})   // later arguments win
println("r == t:", r == t)
println("t.fizz =", t.fizz, "t.buzz =", t.buzz)

try {
  t.__update()          // at least one argument is required
} catch (e) {
  println("t.__update() throws:", e)
}

try {
  t.__update("not a table")
} catch (e) {
  println("t.__update(\"not a table\") throws:", e)
}

Output:

r == t: true
t.fizz = 10 t.buzz = 2
t.__update() throws: wrong number of parameters passed to native closure '__update' (1 passed, at least 2 required)
t.__update("not a table") throws: parameter 1 of '__update' has an invalid type 'string' ; expected: 'table|class|instance'