Reduce the variables exposed in the Runfile environment.

Author: schmich

runx.rb

@@ -122,7 +122,8 @@ def run_task(name, *args)
 
   def load_tasks(file)
     context = TaskContext.new(File.dirname(file), self)
-    InstanceBinding.for(context).eval(File.read(file), file)
+    proxy = TaskContextProxy.new(context)
+    InstanceBinding.for(proxy).eval(File.read(file), file)
     context.tasks
   end
 end
@@ -138,6 +139,28 @@ def self.create
   end
 end
 
+class TaskContextProxy
+  def initialize(real)
+    @_ = real
+  end
+
+  def auto
+    @_.auto
+  end
+
+  def dir(base, relative = '.')
+    @_.dir(base, relative)
+  end
+
+  def doc(doc)
+    @_.doc(doc)
+  end
+
+  def run(*args, &block)
+    @_.run(*args, &block)
+  end
+end
+
 class TaskContext
   def initialize(root_dir, manager)
     @tasks = {}