Commands4A for Discord4J (C4A4D4J)

A Commands4A implementation for processing Discord4J commands.

Usage

Obtaining a Command Engine

The engine is instantiated by calling the CommandEngineProvider API with the appropriate engine descriptor.

CommandEngine<CmdCtx> engine = CommandEngineProvider.getEngine(C4A4D4J.DESCRIPTOR);
engine.scan("package.of.commands");

Alternatively, you can call scan() without any arguments to scan the entire classpath. This isn't recommended, since it can be extremely memory-inefficient.

Defining a Command

Commands are defined as static methods in a scanned class with annotations providing data about the command.

@Command(name="say", usage="<message> [repetitions]")
@Alias("echo") @Alias("print")
@Desc("Prints a provided message.")
@Prereq("perm:manage_server")
public static void commandSay(CmdCtx ctx, String message, @Omittable Integer repetitions) {
    if (repetitions == null)
        repetitions = 1;
    for (int i = Math.max(repetitions, 1); i > 0; i--)
        ctx.getChannel().sendMessage(message);
}

Arguments are discovered using reflection, and are parsed automatically. An InvalidSyntaxException is thrown if provided arguments don't match the expected arguments. This behaviour can be overridden by annotating an argument with the @Omittable annotation, marking it as optional.

Executing a Command

To execute a command, construct an approprtiate command context, then call CommandEngine#execute.

engine.execute(new CmdCtx(event), event.getMessage().getContent());

Available Argument Types

These are the possible types for automatic command argument resolvation:

• Integer
• Float
• Double
• IUser
• IChannel
• String
• CodeBlock
• InlineCodeBlock
• CommandExecution

There are also some special arguments that aren't parsed from the user's input, but instead supply data about the command execution environment.

• String[] supplies the original argument list passed by the user.
• CmdCtx supplies the command's context.