3.1 Inserting Variables

While restricted code may be completely self-contained, it's common for it to require other data: perhaps a tuple listing various available plug-ins, or a dictionary mapping symbols to values. For simple Python data types, such as numbers and strings, the natural solution is to insert variables into one of the namespaces used by the restricted environment, binding the desired variable name to the value.

Continuing from the examples above, you can get the dictionary corresponding to the restricted module named module_name with the following code:

module = r_env.add_module(module_name)
mod_dict = module.__dict__

Despite its name, the add_module() method actually only adds the module if it doesn't already exist; it returns the corresponding module object, whether or not the module had to be created.

Most commonly, you'll insert variable bindings into the __main__ or __builtins__ module, so these will be the most frequent values of module_name.

Once you have the module's dictionary, you need only insert a key/value pair for the desired variable name and value. For example, to add a username variable:

mod_dict['username'] = "Kate Bush"

Restricted code will then have access to this variable.