1 files changed, 49 insertions, 0 deletions
diff --git a/Library/Homebrew/cmd/switch.rb b/Library/Homebrew/cmd/switch.rb
new file mode 100755
index 000000000..a626aaf4c
--- /dev/null
+++ b/Library/Homebrew/cmd/switch.rb
@@ -0,0 +1,49 @@
+require 'formula'
+require 'keg'
+
+module Homebrew
+  def switch
+    if ARGV.named.length != 2
+      onoe "Usage: brew switch <formula> <version>"
+      exit 1
+    end
+
+    name = ARGV.shift
+    version = ARGV.shift
+
+    # Does this formula have any versions?
+    f = Formula.factory(name.downcase)
+    cellar = f.prefix.parent
+    unless cellar.directory?
+      onoe "#{name} not found in the Cellar."
+      exit 2
+    end
+
+    # Does the target version exist?
+    unless (cellar+version).directory?
+      onoe "#{name} does not have a version \"#{version}\" in the Cellar."
+
+      versions = cellar.subdirs.map { |d| Keg.new(d).version }
+      puts "Versions available: #{versions.join(', ')}"
+
+      exit 3
+    end
+
+    # Unlink all existing versions
+    cellar.subdirs.each do |v|
+      keg = Keg.new(v)
+      puts "Cleaning #{keg}"
+      keg.unlink
+    end
+
+    # Link new version, if not keg-only
+    if f.keg_only?
+      keg = Keg.new(cellar+version)
+      keg.optlink
+      puts "Opt link created for #{keg}"
+    else
+      keg = Keg.new(cellar+version)
+      puts "#{keg.link} links created for #{keg}"
+    end
+  end
+end