[Pydev-code] changing python interpreter and project's python path programmatically

[Josh S. <str...@gm...>]

After digging around with the pydev code I've been trying to write a
simple eclipse plugin that can change the active python interpreter or
alter the current project's python path programmatically.  For
example, if I call PythonInterpreterManager.createInterpreterInfo(), I
get the popup asking for which system libs to include on the path.
With the info I get back, I can call addInterpreterInfo() to store it
in the manager.  What I don't understand though is what happens with
this stored data.  For example, if I call
PythonInterpreterManager.getInterpreterInfos(), I don't get that new
info I just added back.  Looking at the code, it seems to be doing
something more complex than just pulling from a list.  I also don't
see anything outside the preferences as to which interpreter is
actually being used.  Is it the selected one?  Is there a way to query
this without actually looking at the IPreferencePage?  Because we have
several diferrent interpreters, I'd like to write a view plugin that
can add/switch-between the various interpreters without having to open
up the preferences window.  However, it seems that the preferences are
intimately tied to the actual data, so I have to actually look at
preferences pages instead of some function on a manager like
getActiveInterpreter() or setActiveInterpreter().

In a related vein, I'd like to be able to alter the pythonpath for a
given project I'm working on.  For example, I might add a checkbox to
my view and when it's toggled, it adds/removes some path from the
project's python path.

I was expecting some functions like addInterpreterPath() on some
manager that adds that path to the interpreters preferences page.  Or
getProjectPythonPath(IProject) or setProjectPythonPath(IProject,
String) that could change the project's python path without dealing
with the actual preference pages.  Just from my limited understanding
of the code, however, a lot of the "model" state is actually in the UI
itself instead of just in the managers.

Is this functionality currently possible with the existing API without
having to jump through a bunch of hoops?

Thanks, Josh