+
Pydertron is a high-level wrapper for Pydermonkey that +provides convenient, secure object wrapping between JS and Python +space.
+
The JsSandbox class encapsulates a JavaScript runtime, context, global +object, and a simple SecurableModule implementation that complies +with the CommonJS standard. It also provides a high-level bridge between +Python and JavaScript so that you don't need to deal with any of the +low-level details of the Pydermonkey API.
+
For instance, here we'll create a JsSandbox whose module root +points to the monkeys SecurableModule compliance test over HTTP:
+
+
+>>> url = ("http://interoperablejs.googlecode.com/svn/trunk/"
+...        "compliance/monkeys/")
+>>> sandbox = JsSandbox(HttpFileSystem(url))
+
+
+
This compliance test requires a global sys object that contains one +method, print(), that takes two arguments. First, we'll create the +print() function and prepare it for exposure to JS code:
+
+
+>>> @jsexposed
+... def jsprint(message, label):
+...   print message, label
+
+
+
Note the use of the @jsexposed decorator: all this does is set +the function's __jsexposed__ attribute to True. This is +done for security purposes: only Python callables satisfying this +criteria will be exposed to JavaScript code, to ensure that +untrusted JS can't accidentally gain access to privileged Python +functionality.
+
Creating a JS object can be done like this:
+
+
+>>> system = sandbox.new_object()
+
+
+
We can now access and set properties on this object via either +item or attribute lookup, just like in JavaScript. Because +print is a reserved word in Python, though, we'll use item +lookup to set the property here:
+
+
+>>> system['print'] = jsprint
+
+
+
Now we tell the sandbox that we want the sys object to be a +global:
+
+
+>>> sandbox.set_globals(sys = system)
+
+
+
And finally, we execute the compliance test by running a one-line +script that imports the 'program' module, like so:
+
+
+>>> sandbox.run_script("require('program');")
+PASS monkeys permitted pass
+DONE info
+0
+
+
+
Note the 0 in the last line: this is the return value of +sandbox.run_script(), which returns 0 on success, and +-1 if an exception was raised. For instance, the output of bad +code looks like this:
+
+
+>>> sandbox.run_script("(function foo() { bar(); })();",
+...                    stderr=sys.stdout)
+Traceback (most recent call last):
+  File "<string>", line 1, in <module>
+  File "<string>", line 1, in foo
+ReferenceError: bar is not defined
+-1
+
+
+
Note that the traceback displayed is actually referring to +JavaScript code: one of Pydertron's helpful conveniences is that +it makes debugging JS code as much like debugging Python code as +possible.
+