KeyValuePair in JS

Unity Engine
1

Is there any way to use KeyValuePair in JS and if so what is the proper syntax?

Thanks in advance for any help.

Mitch

2

I’ll take a guess here since I don’t use JavaScript:

var pair : System.Collections.Generic.KeyValuePair.<string, int> = new System.Collections.Generic.KeyValuePair.<string, int>("key", 9000);
3

Works like a charm. Thanks FizixMan!

4

One last question - the KeyValuePair works fine - but how do I make that into a List? I have a C# example - what would be the JS equivalent?

I can’t seem to figure out the syntax. Thanks for any help.

IList<KeyValuePair<float, Agent>> agentNeighbors_ = new List<KeyValuePair<float, Agent>>();
5

Do you really want to make an IList of those? Would an IDictionary be better managed (forces unique keys)?

Either way, List:
… I… wait a second. I’m not sure at all. Maybe… this?

var agentNeightbours : IList.<KeyValuePair.<float, Agent>> = new List.<KeyValuePair.<float, Agent>>();

Dictionary:

 var agentNeightbours : IDictionary.<float, Agent> = new Dictionary.<float, Agent>();

EDIT: you may need to include the “System.Collections.Generic” namespace into your JS file as well.

6

Was just doing some Dictionary stuff this morning and I can confirm that this is required (at least when using C#).

7

Can’t seem to get it right.

var list : List.<System.Collections.Generic.KeyValuePair.<int, int>> = new
List.<System.Collections.Generic.KeyValuePair.<int, int>>();

No worky :frowning:

Anyone with any thoughts? Is there a way to do this in JavaScript?

Thanks for any help.

Mitch

8

Bump.

Anyone have any insight as to how to get a KeyValuePair to work in JS? The following code throws errors in the log:

var list : List.<System.Collections.Generic.KeyValuePair.<int, int>>;

Thanks for any help.

Mitch

9

Again, do you need to have a List of KeyValuePairs? What is it that you’re trying to accomplish?

10

Yes - a List of KeyValuePairs. The syntax we came up with yesterday throws errors on the log.

I’m trying to convert a C# program to JS. The List of KeyValuePairs is the only thing that has me stumped.

11

Maybe this is just a limitation of the syntax the Unity devs added to JavaScript.

Do your KeyValuePairs have multiple types or are they always <int,int>? If so you could always roll your own:

public class IntIntKeyValuePair
{
	var Key : int;
	var Value : int;
	public IntIntKeyValuePair(var key : int, var value : int)
	{
		this.Key = key;
		this.Value = value;
	}
}

var set : List.<IntIntKeyValuePair> = new List.<IntIntKeyValuePair>();
set.Add(new IntIntKeyValuPair(1, 9000));

Debug.Log("KEY: " + set[0].Key);
Debug.Log("Value: " + set[0].Value);

By the way, do your KeyValuePairs have unique keys? Or are there duplicates?

EDIT: just realized, KeyValuePair is a struct, so rolling your own class like this will have different behavioural implications to consider than a KeyValuePair.

12

I was using <int,int> just for simplicity at this point. You may be right - this could be a limitation of UnityScript. If anyone knows different, please chime in.

I was thinking of rolling my own class - your example looks great - thanks Fizix - I’ll go ahead and give it a whirl!

13

Just be careful, there are some differences between that and KeyValuePair, for example:

var kvp : KeyValuePair.<int, int> = new KeyValuePair.<int, int>(1, 1);
var kvp2 : KeyValuePair.<int, int> = new KeyValuePair.<int, int>(1, 1);
Debug.Log("ARE EQUAL: " + (kvp == kvp2)); //true


var kvp : IntIntKeyValuePair = new IntIntKeyValuePair(1, 1);
var kvp2 : IntIntKeyValuePair = new IntIntKeyValuePair(1, 1);
Debug.Log("ARE EQUAL: " + (kvp == kvp2)); //false


var kvp : KeyValuePair.<int, int> = new KeyValuePair.<int, int>(1, 1);
var kvp2 : KeyValuePair.<int, int> = kvp;
kvp2.Key = 9000;
Debug.Log("KEYS: " + kvp.Key + " -> " + kvp2.Key);//KEYS: 1 -> 9000

var kvp : IntIntKeyValuePair = new IntIntKeyValuePair(1, 1);
var kvp2 : IntIntKeyValuePair = kvp
kvp2.Key = 9000;
Debug.Log("KEYS: " + kvp.Key + " -> " + kvp2.Key);//KEYS: 9000 -> 9000
14

Thanks for the heads up. I’ll continue to see if KeyValuePair is valid in JS while I roll my own class for now.

15

There is also Hashtable. That is what I have been using.

var hash : HashTable = HashTable();
16

Well if MitchStan’s KeyValuePairs have unique keys, then he should be using Dictionary.

17

hashtable is not type fixed, which also means you get no type error checking at compile time … thats the main reason you use generics, that you have a defined state at any time as incorrect data will fire errors already on compile :slight_smile:

hashtable is good for string → string / numeric storage but basically only there (or if you have no plan what generics are naturally or are to lazy to learn it or need a generic type independent data contrainer for network serialization)