子命令

The Builder supports hierarchical command structure like this:

• /mail （父命令）

  • /mail send （子命令）

  • /mail read （子命令）

Every child command is a separate Command and can be created in the same way as a regular command is.

import org.spongepowered.api.command.Command;

Command.Paramertized readCmd = Command
    .builder()
    .permission("myplugin.mail.read")
    .shortDescription(Component.text("Read your inbox"))
    .executor(...)
    .build();

Command.Paramertized sendCmd = Command
    .builder()
    .permission("myplugin.mail.send")
    .shortDescription(Component.text("Send a mail"))
    .addParameter(...)
    .executor(...)
    .build();

Instead of registering them to the event, child commands are registered on their parent command using the Builder#addChild(Command, String, String…) method. They are registered with a list of aliases. The first alias supplied is the primary one and will appear in the usage message.

Command.Paramertized mailCommand = Command.builder()
    .permission("myplugin.mail.base")
    .shortDescription(Component.text("Send and receive mails"))
    .child(readCmd, "read", "r", "inbox")
    .child(sendCmd, "send", "s", "write")
    .build();

回退行为

If a command has child commands, a CommandExecutor, set through Builder#executor(CommandExecutor), and the parameters for the executor become optional.

What happens with errors in selection and argument parsing of child commands is dependent on whether this parent executor exists. If a parent executor has not been set, and if the requested child command could not be found or the arguments cannot be parsed, then an ArgumentParseException will be thrown.

警告

If an ArgumentParseException is not handled, then the Minecraft Brigadier system will tell the user that the command doesn’t exist.

If the child executor throws an exception, the fallback executor is not executed and the error message from the child executor is displayed.