Refactor command handling code

Don’t rely on having external commands always present in the PATH in
order to find them. Instead, provide an accessory method to Tap so
they can be added and used when needed.

While we’re here, do some general refactoring and cleanup of the
command code in these places.

1 files changed, 10 insertions, 9 deletions

diff --git a/Library/Homebrew/cmd/command.rb b/Library/Homebrew/cmd/command.rb
index 39e8ba6fc..d964fa1a9 100644
--- a/Library/Homebrew/cmd/command.rb
+++ b/Library/Homebrew/cmd/command.rb
@@ -8,15 +8,16 @@ module Homebrew
 
   def command
     abort "This command requires a command argument" if ARGV.empty?
-    cmd = ARGV.first
-    cmd = HOMEBREW_INTERNAL_COMMAND_ALIASES.fetch(cmd, cmd)
 
-    if (path = Commands.path(cmd))
-      puts path
-    elsif (path = which("brew-#{cmd}") || which("brew-#{cmd}.rb"))
-      puts path
-    else
-      odie "Unknown command: #{cmd}"
-    end
+    cmd = HOMEBREW_INTERNAL_COMMAND_ALIASES.fetch(ARGV.first, ARGV.first)
+
+    path = Commands.path(cmd)
+
+    cmd_paths = PATH.new(ENV["PATH"]).append(Tap.cmd_directories) unless path
+    path ||= which("brew-#{cmd}", cmd_paths)
+    path ||= which("brew-#{cmd}.rb", cmd_paths)
+
+    odie "Unknown command: #{cmd}" unless path
+    puts path
   end
 end