CLI package update 1 (#2019)

Features added:
   - string_seq option and arg value type for repeated strings collected into a sequence.
   - Command fullname() to make it easier to match on command name.
   - Checking commands are leaves so that partial commands return syntax errors.

Other changes:
   - Tests for the above.
   - _ValueType is now a trait instead of a union. This makes it easier to delegate type specific work to one place, and makes value type more easily extended.
   - A few other cleanups, like the removal of redundant box modifiers on methods.

CHANGELOG.md

@@ -15,6 +15,16 @@ All notable changes to the Pony compiler and standard library will be documented
 
 ### Added
 
+- Add cli package implementing the CLI syntax ([RFC #38](https://github.com/ponylang/rfcs/blob/master/text/0038-cli-format.md)) 
+   - Initial ([PR #1897](https://github.com/ponylang/ponyc/pull/1897)) implemented the full RFC and contained:
+      - Enhanced Posix / GNU program argument syntax.
+      - Commands and sub-commands.
+      - Bool, String, I64 and F64 option / arg types.
+      - Help command and syntax errors with formatted output.
+   - Update ([PR #2019](https://github.com/ponylang/ponyc/pull/2019)) added:
+      - String-seq (ReadSeq[String]) types for repeated string options / args.
+      - Command fullname() to make it easier to match on unique command names.
+      - Checking that commands are leaves so that partial commands return syntax errors.
 
 
 ### Changed
@@ -75,12 +85,12 @@ All notable changes to the Pony compiler and standard library will be documented
 
 - Compiler error instead of crash for invalid this-dot reference in a trait. ([PR #1879](https://github.com/ponylang/ponyc/pull/1879))
 - Compiler error instead of crash for too few args to constructor in case pattern. ([PR #1880](https://github.com/ponylang/ponyc/pull/1880))
-- Pony runtime hashmap bug that resulted in issues [#1483](https://github.com/ponylang/ponyc/issues/1483), [#1781](https://github.com/ponylang/ponyc/issues/1781), and [#1872](https://github.com/ponylang/ponyc/issues/1872). ([PR #1886](https://github.com/ponylang/ponyc/pull/1886)) 
+- Pony runtime hashmap bug that resulted in issues [#1483](https://github.com/ponylang/ponyc/issues/1483), [#1781](https://github.com/ponylang/ponyc/issues/1781), and [#1872](https://github.com/ponylang/ponyc/issues/1872). ([PR #1886](https://github.com/ponylang/ponyc/pull/1886))
 - Compiler crash when compiling to a library ([Issue #1881](https://github.com/ponylang/ponyc/issues/1881))([PR #1890](https://github.com/ponylang/ponyc/pull/1890))
 
 ### Changed
 
-- TCPConnection.connect_failed, UDPNotify.not_listening, TCPListenNotify.not_listening no longer have default implementation. The programmer is now required to implement error handling or consciously choose to ignore. ([PR #1853](https://github.com/ponylang/ponyc/pull/1853) 
+- TCPConnection.connect_failed, UDPNotify.not_listening, TCPListenNotify.not_listening no longer have default implementation. The programmer is now required to implement error handling or consciously choose to ignore. ([PR #1853](https://github.com/ponylang/ponyc/pull/1853)
 
 ## [0.13.2] - 2017-04-29
 

examples/commandline/main.pony

@@ -2,46 +2,35 @@ use "cli"
 
 actor Main
   new create(env: Env) =>
-    try
-      let cmd =
-        match CommandParser(cli_spec()).parse(env.args, env.vars())
-        | let c: Command => c
-        | let ch: CommandHelp =>
-            ch.print_help(env.out)
-            env.exitcode(0)
-            return
-        | let se: SyntaxError =>
-            env.out.print(se.string())
-            env.exitcode(1)
-            return
-        end
+    let cs =
+      try
+        CommandSpec.leaf("echo", "A sample echo program", [
+          OptionSpec.bool("upper", "Uppercase words"
+            where short' = 'U', default' = false)
+        ], [
+          ArgSpec.string_seq("words", "The words to echo")
+        ]).>add_help()
+      else
+        env.exitcode(-1)  // some kind of coding error
+        return
+      end
 
-        // cmd is a valid Command, now use it.
+    let cmd =
+      match CommandParser(cs).parse(env.args, env.vars())
+      | let c: Command => c
+      | let ch: CommandHelp =>
+          ch.print_help(env.out)
+          env.exitcode(0)
+          return
+      | let se: SyntaxError =>
+          env.out.print(se.string())
+          env.exitcode(1)
+          return
+      end
 
+    let upper = cmd.option("upper").bool()
+    let words = cmd.arg("words").string_seq()
+    for word in words.values() do
+      env.out.write(if upper then word.upper() else word end + " ")
     end
-
-  fun tag cli_spec(): CommandSpec box ? =>
-    """
-    Builds and returns the spec for a sample chat client's CLI.
-    """
-    let cs = CommandSpec.parent("chat", "A sample chat program", [
-      OptionSpec.bool("admin", "Chat as admin" where default' = false)
-      OptionSpec.string("name", "Your name" where short' = 'n')
-      OptionSpec.i64("volume", "Chat volume" where short' = 'v')
-    ], [
-      CommandSpec.leaf("say", "Say something", Array[OptionSpec](), [
-        ArgSpec.string("words", "The words to say")
-      ])
-      CommandSpec.leaf("emote", "Send an emotion", [
-        OptionSpec.f64("speed", "Emote play speed" where default' = F64(1.0))
-      ], [
-        ArgSpec.string("emotion", "Emote to send")
-      ])
-      CommandSpec.parent("config", "Configuration commands", Array[OptionSpec](), [
-        CommandSpec.leaf("server", "Server configuration", Array[OptionSpec](), [
-          ArgSpec.string("address", "Address of the server")
-        ])
-      ])
-    ])
-    cs.add_help()
-    cs
+    env.out.print("")