Proxied commandsenders

The CommandAPI has extra support for vanilla Minecraft's /execute command, by allowing the CommandSender to be an instance of the ProxiedCommandSender class. This allows the CommandSender to contain two extra pieces of information: The "proxied sender" and the original sender.

Example - Running a command as a chicken

Say we have a command which kills the sender of a command. This is easily implemented as follows:

new CommandAPICommand("killme")
    .executesPlayer((player, args) -> {
        player.setHealth(0);
    })
    .register();

CommandAPICommand("killme")
    .executesPlayer(PlayerCommandExecutor { player, _ ->
        player.setHealth(0.0)
    })
    .register()

But what if the sender of the command is not a player? By using Minecraft's /execute command, we could execute the command as any arbitrary entity, as shown with the command below:

/execute as @e[type=chicken] run killme

To handle this case, we can use the .executesProxy() method to ensure that the command sender is a ProxiedCommandSender. Then, we can kill the callee (the entity which is being 'forced' to run the command /killme)

new CommandAPICommand("killme")
    .executesPlayer((player, args) -> {
        player.setHealth(0);
    })
    .executesProxy((proxy, args) -> {
        // Check if the callee (target) is an Entity and kill it
        if (proxy.getCallee() instanceof LivingEntity target) {
            target.setHealth(0);
        }
    })
    .register();

CommandAPICommand("killme")
    .executesPlayer(PlayerCommandExecutor { player, _ ->
        player.setHealth(0.0)
    })
    .executesProxy(ProxyCommandExecutor { proxy, _ ->
        // Check if the callee (target) is an Entity and kill it
        if (proxy.callee is LivingEntity) {
            (proxy.callee as LivingEntity).setHealth(0.0)
        }
    })
    .register()

This allows the command above to run successfully, killing all chickens it can find.