Getting to the dynamic value generator of a Dynamic parameter

One thing that has frequently aggravates me about param is that there is no way (that I know of) to get at a dynamic value generator e.g a numbergen object. Perhaps there is a proper way to do this, but I have hacked in this method into my copy of param (on the Dynamic class) for the time being:

``` python
def get_generator(self, obj):
"""
Given a parameterized object, gets the dynamic value generator.
"""
return super(Dynamic,self).__get__(obj, obj.__class__)
```

This is still awkward to use, but better than nothing. Say I have an `imagen.Gaussian` object and I want to fiddle the random number generator used for the orientation. Now I can do:

``` python
generator = gaussian.params('orientation').get_generator(gaussian)
```

Now for instance, I could change the `time_fn` for this numbergen object.

Any thoughts? Is there already a better way of doing this?