[Suggestion] Optional Arguments

[Speiger]

Ok this is a bit rough to start.

When commands in Minecraft are created, you have either 2 ways of creating commands that are executed.
Either implement every single execution itself. (If you have 5 optional parameters that's getting annoying really quickly)
Or you implement a CommandContext Wrapper that basically does this:

	public boolean hasValue(String id, Class<?> type)
	{
		try
		{
			return source.getArgument(id, type) != null;
		}
		catch(Exception e)
		{
			return false;
		}
	}
	
	public <T> T getOrDefault(String id, Class<T> type, T defaultValue)
	{
		try
		{
			return source.getArgument(id, type);
		}
		catch(Exception e)
		{
		}
		return defaultValue;
	}

It would be nice if you could check if arguments have been defined or allow to getOrDefault.
This is mainly there to reduce code. Implementing everything 5 times. Even if Lambdas are being used that call a helper function that basically does the same.
Instead this could look a lot cleaner.

Here is a example with my CommandBuilder & Command Wrapper

	public static CommandBuilder createGenStart()
	{
		CommandBuilder builder = new CommandBuilder("gen");
		//Normal Gen
		Command<CommandSource> radius = GenCommand::executeRadius;
		builder.addLiteral("radius");
		builder.addArgument("Task Name", StringArgumentType.word());
		builder.addArgument("Shape", StringArgumentType.word(), GenCommand::listShape);
		builder.addArgument("Center", ColumnPosArgument.columnPos(), CenterArgument::listSimpleSuggestion);
		builder.addArgument("Radius", IntegerArgumentType.integer(1, 25000), radius);
		builder.addArgument("Dimension", DimensionArgument.getDimension(), radius); //Optional
		builder.addArgument("Generation Type", StringArgumentType.word(), GenCommand::listSuggestions, radius).popTop(); //PopTop basically goes down the logic tree allowing to make a new branch. A single/multi pop exists too.
		
		Command<CommandSource> expansion = GenCommand::executeExpansion;
		builder.addLiteral("expansion");
		builder.addArgument("Task Name", StringArgumentType.word());
		builder.addArgument("Shape", StringArgumentType.word(), GenCommand::listShape);
		builder.addArgument("Center", ColumnPosArgument.columnPos(), CenterArgument::listSimpleSuggestion);
		builder.addArgument("Min Radius", IntegerArgumentType.integer(1));
		builder.addArgument("Max Radius", IntegerArgumentType.integer(1), expansion);
		builder.addArgument("Dimension", DimensionArgument.getDimension(), expansion);
		builder.addArgument("Generation Type", StringArgumentType.word(), GenCommand::listSuggestions, expansion).popTop();
		return builder;
	}
	
	private static int executeRadius(CommandContext<CommandSource> source)
	{
		CommandWrapper wrapper = new CommandWrapper(source);
		String name = wrapper.get("Task Name", String.class);
		GenShape shape = wrapper.hasValue("Shape", String.class) ? GenShape.valueOf(wrapper.get("Shape", String.class)) : wrapper.get("Shape", GenShape.class);
		BlockPos center = CenterArgument.getVanillaBlockPos(wrapper.get("Center", ILocationArgument.class), source.getSource());
		int radius = wrapper.get("Radius", Integer.class);
		ResourceLocation dimension = wrapper.getOrDefault("Dimension", ResourceLocation.class, wrapper.getSource().getWorld().getDimensionKey().getLocation());
		return 0;
	}

The Reason for hasValue is used for the GenShape is a example. What if the software that the CommandContext uses only exists on 1 side. It can detect if a single side exists, or if dual sided implementation is present.
Or in modding terms: ServerOnly Mods.

This is how I would implement it.
If you want I can make it a offical PR, or you can just grab the implementation.
Reference Code: https://github.com/Mojang/brigadier/blob/master/src/main/java/com/mojang/brigadier/context/CommandContext.java#L81

    public <V> boolean hasArgument(final String name, final Class<V> clazz) {
        final ParsedArgument<S, ?> argument = arguments.get(name);

        if (argument == null) {
            return false;
        }
        final Object result = argument.getResult();
        if (PRIMITIVE_TO_WRAPPER.getOrDefault(clazz, clazz).isAssignableFrom(result.getClass())) {
            return true;
        } else {
            return false;
        }
    }
	
    public <V> V getArgument(final String name, final Class<V> clazz, V defaultValue) {
        final ParsedArgument<S, ?> argument = arguments.get(name);

        if (argument == null) {
            return defaultValue;
        }

        final Object result = argument.getResult();
        if (PRIMITIVE_TO_WRAPPER.getOrDefault(clazz, clazz).isAssignableFrom(result.getClass())) {
            return (V) result;
        } else {
            return defaultValue;
        }
    }

[Gamebuster19901]

Are redirects not a solution for this?

[Speiger]

@Gamebuster19901 the point is: You are required to write duplicated implementations for every single Optional argument.
Or write a specific handler that redirects to a function where you insert the default argument.
Causing for a LOT of code duplication. 1 function where you handle everything, including Default Arguments is a lot simpler to deal with and also a lot easier to read.

Just look at my code example that I have done and replicate it and look how much worse it looks and is to maintain if you don't have these features.

I dunno what you think but if you have 8 versions to maintain and have to do fixes for one or two functions that have to interact with that it just gets bad.
This is why i have added a wrapper for myself that allows for this kind of functionality, to make this possible.

And it is quite sad that Mojang doesn't see the Benefit of such a function that doesn't have ANY downsides.

[KitsuneAlex]

Giving this a friendly bump because this would be lovely

[LoboMetalurgico]

Yes, please! We need this!

[M4ximumPizza]

This would make this type of development significantly faster.

[Speiger]

Honestly this is just a very tiny QoL change that is "Optional" yet mojang hasn't included.
I don't expect Mojang to ever include this.