add dependencies for Homebrew formulae

CONTRIBUTING.md

@@ -98,6 +98,7 @@ Additional fields you might need for special use-cases:
 | `binary`           | relative path to a binary that should be linked into the `~/usr/local/bin` folder on installation
 | `input_method`     | relative path to a input method that should be linked into the `~/Library/Input Methods` folder on installation
 | `nested_container` | relative path to an inner container that must be extracted before moving on with the installation; this allows us to support dmg inside tar, zip inside dmg, etc.
+| `depends_on_formula` | a list of Homebrew Formulae upon which this Cask depends
 | `caveats`          | a string or Ruby block providing the user with Cask-specific information at install time (see __Caveats Details__ for more information)
 | `after_install`    | a Ruby block containing postflight install operations
 | `after_uninstall`  | a Ruby block containing postflight uninstall operations

FAQ.md

@@ -18,11 +18,12 @@ Casks currently have five required fields:
  * __font__ : (required for fonts) indicates which file(s) should be linked into the Fonts folder on installation
  * __input_method__: (required for input method) indicates which file(s) should be linked into the Input Methods folder on installation
 
-and five optional fields:
+and six optional fields:
 
 * __binary__: relative path to a binary to be installed
 * __uninstall__: (optional for `.pkg`) indicates how to uninstall a package
 * __nested_container__: relative path to a nested inner container
+* __depends_on_formula__: a list of Homebrew Formulae upon which this Cask depends
 * __caveats__: a string or Ruby block providing the user with Cask-specific information at install time
 * __after_install__: a Ruby block containing postflight install operations
 * __after_uninstall__: a Ruby block containing postflight uninstall operations

lib/cask/dsl.rb

@@ -12,6 +12,8 @@ def url; self.class.url; end
 
   def version; self.class.version; end
 
+  def depends_on_formula; self.class.depends_on_formula; end
+
   def sums; self.class.sums || []; end
 
   def artifacts; self.class.artifacts; end
@@ -33,6 +35,10 @@ def version(version=nil)
       @version ||= version
     end
 
+    def depends_on_formula(*args)
+      @depends_on_formula ||= args
+    end
+
     def artifacts
       @artifacts ||= Hash.new { |hash, key| hash[key] = Set.new }
     end

lib/cask/installer.rb

@@ -1,4 +1,6 @@
 require 'digest'
+require 'dependency_collector'
+require 'formula_installer'
 
 class Cask::Installer
   def initialize(cask, command=Cask::SystemCommand)
@@ -27,6 +29,7 @@ def install(force=false)
     print_caveats
 
     begin
+      formula_dependencies
       download
       extract_primary_container
       install_artifacts
@@ -60,6 +63,29 @@ def install_artifacts
     end
   end
 
+  def formula_dependencies
+    unless @cask.depends_on_formula.empty?
+      ohai 'Installing Formula dependencies from Homebrew'
+      @cask.depends_on_formula.each do |dep_name|
+        dependency_collector = DependencyCollector.new
+        dep = dependency_collector.add(dep_name)
+        unless dep.installed?
+          dep_tab = Tab.for_formula(dep.to_formula)
+          dep_options = dep.options
+          dep = dep.to_formula
+          fi = FormulaInstaller.new(dep)
+          fi.tab = dep_tab
+          fi.options = dep_options
+          fi.ignore_deps = false
+          fi.show_header = true
+          fi.install
+          fi.caveats
+          fi.finish
+        end
+      end
+    end
+  end
+
   def print_caveats
     self.class.print_caveats(@cask)
   end