Let's say I have a variety of objects with the following data structure:
{
namespace: 'first'|'second'|'third'
}
Now, I need to include another object with the same data structure, but its namespace cannot be assigned as 'first'|‘second’|'third'. It must use a new namespace.
How do I accomplish this task?
Furthermore, when adding yet another object, how can I restrict the namespace value?
interface Namespaced<K extends string> {
namespace: K;
}
const nsMap = new Map<string, Namespaced<any>>()
function addNamespace<K extends string, V extends Namespaced<K>>(
ns: V
): V {
if (nsMap.has(ns.namespace)) {
throw new Error(`Attempting to create duplicate namespace "${ns.namespace}"`)
}
nsMap.set(ns.namespace, ns);
return ns;
}
let a = addNamespace({namespace: 'a'})
// ^?
let b = addNamespace({namespace: 'b', x: 'b'})
// ^?
let c = addNamespace({namespace: 'a'}) // throws [ERR]: Attempting to create duplicate namespace "a"
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