Command Line Subcommands in CLIPS

Here’s the translation of the Go code example to Java, formatted in Markdown suitable for Hugo:

Our first program will demonstrate command-line subcommands, each with its own set of flags. This is similar to how tools like git have subcommands like git commit and git push, each with their own options.

import java.util.Arrays;

public class CommandLineSubcommands {
    public static void main(String[] args) {
        // We use a custom ArgumentParser class to handle subcommands and flags
        ArgumentParser parser = new ArgumentParser();

        // We declare subcommands and their specific flags
        parser.addSubcommand("foo")
              .addFlag("enable", false, "enable")
              .addFlag("name", "", "name");

        parser.addSubcommand("bar")
              .addFlag("level", 0, "level");

        // The subcommand is expected as the first argument to the program
        if (args.length < 1) {
            System.out.println("expected 'foo' or 'bar' subcommands");
            System.exit(1);
        }

        // Check which subcommand is invoked
        String subcommand = args[0];
        String[] subcommandArgs = Arrays.copyOfRange(args, 1, args.length);

        switch (subcommand) {
            case "foo":
                parser.parse("foo", subcommandArgs);
                System.out.println("subcommand 'foo'");
                System.out.println("  enable: " + parser.getBoolean("foo", "enable"));
                System.out.println("  name: " + parser.getString("foo", "name"));
                System.out.println("  tail: " + Arrays.toString(parser.getRemainingArgs("foo")));
                break;
            case "bar":
                parser.parse("bar", subcommandArgs);
                System.out.println("subcommand 'bar'");
                System.out.println("  level: " + parser.getInt("bar", "level"));
                System.out.println("  tail: " + Arrays.toString(parser.getRemainingArgs("bar")));
                break;
            default:
                System.out.println("expected 'foo' or 'bar' subcommands");
                System.exit(1);
        }
    }
}

Note: This example uses a custom ArgumentParser class which is not part of the standard Java library. You would need to implement this class to handle subcommands and flags similar to the flag package in the original example.

To compile and run the program:

$ javac CommandLineSubcommands.java
$ java CommandLineSubcommands foo -enable -name=joe a1 a2
subcommand 'foo'
  enable: true
  name: joe
  tail: [a1, a2]

$ java CommandLineSubcommands bar -level 8 a1
subcommand 'bar'
  level: 8
  tail: [a1]

If you try to use flags from one subcommand with another, you’ll get an error:

$ java CommandLineSubcommands bar -enable a1
Error: Unknown flag: -enable
Usage of bar:
  -level int
        level

This Java implementation provides similar functionality to the original example. It demonstrates how to create a command-line application with subcommands, each having its own set of flags. The main differences are:

Java doesn’t have a built-in flag parsing library as sophisticated as Go’s flag package, so we’re using a custom ArgumentParser class.
The structure is more object-oriented, as is typical in Java.
We’re using a switch statement to handle different subcommands, which is similar to the original Go code.

Remember that for a real-world application, you might want to use a more robust command-line parsing library for Java, such as Apache Commons CLI or JCommander.

File Paths in CLIPS

Temporary Files and Directories in CLIPS

Learn X By Example

Title here

Command Line Subcommands in CLIPS