support for loading javascript from file referenced by name

README.rdoc

@@ -22,16 +22,13 @@ Embed the Mozilla Rhino Javascript interpreter into Ruby
 # evaluate some simple javascript
   eval_js "7 * 6" #=> 42
 
-# evaluate bytes read from any File/IO object:
-  File.open("mysource.js") do |file|
-    eval_js file, "mysource.js"
-
-    #or in the context of a controlled scope
-    Rhino::Context.open do |context|
-      context['foo'] = 'some global variable referenced in mysource.js'
-      context.eval(file, "mysource.js")
+# that's quick and dirty, but if you want more control over your
+# environment, use a Context:
+  Rhino::Context.open do |cxt|
+    cxt['foo'] = "bar"
+    cxt.eval('foo') # => "bar"
   end
-  
+
 # evaluate a ruby function from javascript
 
   Rhino::Context.open do |context|
@@ -73,6 +70,21 @@ Embed the Mozilla Rhino Javascript interpreter into Ruby
   Rhino::Context.open(:java => true) do |context|
     context.eval("java.lang.System.exit()") #it's dangerous!
   end
+
+==== Different ways of loading javascript source
+
+In addition to just evaluating strings, you can also use streams such as files.
+
+# evaluate bytes read from any File/IO object:
+  File.open("mysource.js") do |file|
+    eval_js file, "mysource.js"
+  end
+
+# or load it by filename
+  Rhino::Context.open do |context|
+    context.load("mysource.js")
+  end
+
 
 == REQUIREMENTS:
 

lib/rhino/context.rb

@@ -92,7 +92,20 @@ def eval(source, source_name = "<eval>", line_number = 1)
         raise Rhino::RhinoError, e
       end
     end
-
+
+    # Read the contents of <tt>filename</tt> and evaluate it as javascript. Returns the result of evaluating the
+    # javascript. e.g.
+    #
+    # Context.open do |cxt|
+    #   cxt.load("path/to/some/lib.js")
+    # end
+    #
+    def load(filename)
+      File.open(filename) do |file|
+        eval file, filename, 1
+      end
+    end
+
     # Set the maximum number of instructions that this context will execute.
     # If this instruction limit is exceeded, then a Rhino::RunawayScriptError
     # will be raised

spec/rhino/context_spec.rb

@@ -124,7 +124,7 @@ def timesfive(rhs)
     }.should raise_error
   end
 
-  describe "compilation" do
+  describe "loading javascript source into the interpreter" do
 
     it "can take an IO object in the eval method instead of a string" do
       source = StringIO.new(<<-EOJS)
@@ -147,5 +147,16 @@ def timesfive(rhs)
       end
     end
 
+    it "can load a file into the runtime" do
+      mock(:JavascriptSourceFile).tap do |file|
+        File.should_receive(:open).with("path/to/mysource.js").and_yield(file)
+        Context.open do |cxt|
+          cxt.should_receive(:eval).with(file, "path/to/mysource.js", 1)
+          cxt.load("path/to/mysource.js")
+        end
+      end
+
+    end
+
   end
 end