[Zope] How do I eval a variable within the acquisition path?

[Tim Nash]

I apologize for the question (the zope area of my brain must need
coffee) but I can't find the answer in the zope book or in any of the
scripts posted to the zope cookbook.

I want to use a variable in a acquisition path.

So for example, from the zope book on scripts, imagine that
vaccinateplan() printed out a specific animals vaccination plan.

Now instead of saying 'LargeAnimals' and 'hippo' like so:

print context.Vet.LargeAnimals.hippo.vaccinateplan()

I want to do like this:

category = REQUEST.form['category']
animal = REQUEST.form['animal']

print context.Vet.category.animal.vaccinateplan()



but I get an Attribute Error. How do I eval a variable within the
acquisition path?

Thanks,
Tim