brew depstree: shows a tree of dependencies for a formula

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Library/Contributions/examples/brew-depstree.rb

@@ -0,0 +1,21 @@
+require 'formula'
+
+module Homebrew extend self
+  def depstree
+    ARGV.formulae.each do |f|
+      puts f
+      recursive_deps_tree(f, 1)
+      puts
+    end
+  end
+
+private
+  def recursive_deps_tree(formula, level)
+    formula.deps.each do |dep|
+      puts "> "*level+dep
+      recursive_deps_tree(Formula.factory(dep), level+1)
+    end
+  end
+end
+
+Homebrew.depstree