[Grace-core] Undefined Variables

[Andrew P. Black]

On 25 Feb 2015, at 14:15, Kim Bruce <kim at cs.pomona.edu> wrote:

> It sounds like one of those things that will be available, but not made prominent, that is mainly there for tools to use.  (Perhaps we could even issue a warning in any program that uses it.)  At any rate, while I would discourage students from using it, it seems useful for building tools.  It's OK to me tao have it raise an exception.

We could put the definition of the exception (and of the method that tests for undefinedness) in a named module so that they have to be imported explicitly.  This is like mirrors.  

	Andrew