Dependency resolution with fancy syntax

Is it a DSL? No. But people call it that apparently.

To add a dependency:

class Doe <Formula
  depends_on 'ray'
  depends_on 'mee' => :optional
  depends_on 'far' => :recommended
  depends_on Sew.new
end

Sew would be a formula you have defined in this Formula file. This is useful,
eg. see Python's formula. Formula specified in this fashion cannot be linked
into the HOMEBREW_PREFIX, they are considered private libraries. This allows
you to create custom installations that are very specific to your formula.

More features to come, like specifying versions

Library/Homebrew/brew.h.rb

@@ -144,31 +144,12 @@ def clean f
 end
 
 
-# NOTE this is ugly code, and inefficient too, and can have infinite cycles
-# I have no time currently to improve it, feel free to submit a more elegant
-# solution. Thanks! --mxcl
-def expand_deps fae
+def expand_deps ff
   deps = []
-  fae.each do |f|
-    case f.deps
-    when String, Array
-      f.deps.each do |name|
-        f = Formula.factory name
-        deps << expand_deps(f) if f.deps # hideous inefficient
-        deps << f unless f.installed?
-      end
-    when Hash
-      # TODO implement optional and recommended
-      names = []
-      f.deps.each_value {|v| names << v}
-      ff=names.flatten.collect {|name| Formula.factory name}
-      deps << expand_deps(ff)
-    end
-    deps << f
+  ff.deps.collect do |f|
+    deps += expand_deps(Formula.factory(f))
   end
-
-  # TODO much more efficient to use a set and not recurse stuff already done
-  return deps.flatten.uniq
+  deps << ff
 end
 
 

Library/Homebrew/formula.rb

@@ -114,8 +114,6 @@ class Formula
   #     :p2 => ['http://moo.com/patch5', 'http://moo.com/patch6']
   #   }
   def patches; [] end
-  # reimplement and specify dependencies
-  def deps; end
   # sometimes the clean process breaks things, return true to skip anything
   def skip_clean? path; false end
 
@@ -157,6 +155,7 @@ class Formula
   end
 
   def self.factory name
+    return name if name.kind_of? Formula
     require self.path(name)
     return eval(self.class(name)).new(name)
   rescue LoadError
@@ -167,6 +166,10 @@ class Formula
     HOMEBREW_PREFIX+'Library'+'Formula'+"#{name.downcase}.rb"
   end
 
+  def deps
+    self.class.deps or []
+  end
+
 protected
   # Pretty titles the command and buffers stdout/stderr
   # Throws if there's an error
@@ -280,8 +283,30 @@ private
   end
 
   class <<self
-    attr_reader :url, :version, :homepage, :head
+    attr_reader :url, :version, :homepage, :head, :deps
     attr_reader *CHECKSUM_TYPES
+
+    def depends_on name, *args
+      @deps ||= []
+
+      case name
+      when String
+        # noop
+      when Hash
+        name = name.keys.first # indeed, we only support one mapping
+      when Symbol
+        name = name.to_s
+      when Formula
+        @deps << name
+        return # we trust formula dev to not dupe their own instantiations
+      else
+        raise "Unsupported type #{name.class}"
+      end
+
+      # we get duplicates because every new fork of this process repeats this
+      # step for some reason I am not sure about
+      @deps << name unless @deps.include? name
+    end
   end  
 end
 

bin/brew

@@ -38,6 +38,7 @@ unless system "which -s gcc-4.2" and $?.success?
   abort "Sorry, Homebrew requires gcc 4.2, which is provided by Xcode 3.1"
 end
 
+
 begin
   case ARGV.shift
     when '--prefix' then puts HOMEBREW_PREFIX
@@ -104,7 +105,7 @@ begin
         unless system "which #{ENV['CC'] or 'cc'} &> /dev/null" and $?.success?
           raise "We cannot find a c compiler, have you installed the latest Xcode?"
         end
-        fae = ARGV.formulae.reject do |f|
+        formulae = ARGV.formulae.reject do |f|
           if f.installed?
             message = "Formula already installed: #{f.prefix}"
             if ARGV.formulae.count > 1
@@ -115,20 +116,24 @@ begin
             true
           end
         end
-        exit 0 if fae.empty?
+        exit 0 if formulae.empty?
       else
-        fae=ARGV.formulae
+        formulae = ARGV.formulae
       end
 
-      # the resulting order will be optimal for super-deps and deps
-      fae=expand_deps fae
+      deps = []
+      formulae.each { |f| deps += expand_deps f }
+      formulae = deps.reject { |f| f.installed? }
+
+      require 'set'
+      done = Set.new
 
       require 'beer_events'
-
       watch_out_for_spill do
-        fae.each do |f|
-          # we need to ensure a pristine ENV for each process or the formula
-          # will start with the ENV from the previous build
+        formulae.each do |f|
+          next if done.include? f.class
+          done << f.class
+
           pid=fork
           if pid.nil?
             exec __FILE__, "install-just-one", f.name, *ARGV.options