Add options to the cli

Options can be passed on the command-line and/or using
the HOMEBREW_CASK_OPTS environment variable (which has
lowest priority). There is a single --appdir=PATH option
right now, but this commit enables future awesomeness!

Other minor changes:

* `brew cask help` now returns the same thing as `brew cask`
  instead of saying there was “no such command as help”.

* The HEREDOC block now uses Homebrew's #undent instead of the
  customed-rolled #gsub version. Cleaner and more flexible.

* `Cask.set_appdir` has been renamed to `Cask.appdir=`. This
  is more Rubyish, and of little consequence (the only place
  it was previously used was in the tests).

README.md

@@ -109,6 +109,22 @@ packages, so the community part is important! Every little bit counts.
 You can add Casks to your existing (or new) taps: just create a directory named
 `Casks` inside your tap, put your Casks there, and everything will just work.
 
+# Options
+
+You can set options on the command-line and/or using the `HOMEBREW_CASK_OPTS`
+environment variable, e.g.:
+
+```bash
+# This probably should happen in your ~/.{ba|z}shrc
+$ export HOMEBREW_CASK_OPTS="/Applications"
+
+# Installs to /Applications
+$ brew cask install a-cask
+
+# Trumps the ENV and installs to ~/Applications
+$ brew cask install --appdir="~/Applications" a-cask
+```
+
 # Alfred Integration
 
 I've been using Casks along with Alfred to great effect.  Just add

lib/cask.rb

@@ -26,8 +26,8 @@ class Cask
     @appdir ||= Pathname.new(File.expand_path("~/Applications"))
   end
 
-  def self.set_appdir(canned_appdir)
-    @appdir = canned_appdir
+  def self.appdir=(_appdir)
+    @appdir = _appdir
   end
   
   def self.init

lib/cask/cli.rb

@@ -1,3 +1,6 @@
+require 'optparse'
+require 'shellwords'
+
 class Cask::CLI
   def self.commands
     Cask::CLI.constants - ["NullCommand"]
@@ -14,6 +17,7 @@ class Cask::CLI
   def self.process(arguments)
     Cask.init
     command, *rest = *arguments
+    rest = process_options(rest)
     lookup_command(command).run(*rest)
   end
 
@@ -34,6 +38,16 @@ class Cask::CLI
     }
     list.sort
   end
+  
+  def self.process_options(args)
+    allrgs = Shellwords.shellsplit(ENV['HOMEBREW_CASK_OPTS'] || "") + args
+    OptionParser.new do |opts|
+      opts.on("--appdir=MANDATORY") do |v|
+        Cask.appdir = Pathname.new File.expand_path(v)
+      end
+    end.parse!(allrgs)
+    return allrgs
+  end
 
 
   class NullCommand
@@ -43,7 +57,7 @@ class Cask::CLI
 
     def run(*args)
       purpose
-      if @attempted_name
+      if @attempted_name and @attempted_name != "help"
         puts "!! "
         puts "!! no command with name: #{@attempted_name}"
         puts "!! "
@@ -52,7 +66,7 @@ class Cask::CLI
     end
 
     def purpose
-      puts <<-PURPOSE.gsub(/^ {6}/, '')
+      puts <<-PURPOSE.undent
       {{ brew-cask }}
         brew-cask provides a friendly homebrew-style CLI workflow for the
         administration Mac applications distributed as binaries

test/cli/options_test.rb

@@ -0,0 +1,26 @@
+require 'test_helper'
+
+describe Cask::CLI do
+  it "supports setting the appdir" do
+    shutup do
+      Cask::CLI.process %w{help --appdir=/some/path}
+    end
+
+    Cask.appdir.must_equal Pathname.new File.expand_path "/some/path"
+  end
+
+  it "supports setting the appdir from ENV" do
+    ENV['HOMEBREW_CASK_OPTS'] = "--appdir=/some/path"
+
+    shutup do
+      Cask::CLI.process %w{help}
+    end
+
+    Cask.appdir.must_equal Pathname.new File.expand_path "/some/path"
+  end
+
+  after do
+    ENV['HOMEBREW_CASK_OPTS'] = nil
+    Cask.appdir = CANNED_APPDIR
+  end
+end

test/support/fake_appdir.rb

@@ -1,6 +1,6 @@
 # wire in a fake appdir for linkapps
 CANNED_APPDIR = (HOMEBREW_REPOSITORY/"Applications")
-Cask.set_appdir(CANNED_APPDIR)
+Cask.appdir = CANNED_APPDIR
 
 module FakeAppdirHooks
   def before_setup