A simple key-value store for R6::R6 generator objects. On retrieval of an object, the following applies:
R6 Factories (objects of class
R6ClassGenerator) are initialized (with additional arguments).
Functions are called (with additional arguments) and must return an instance of a R6::R6 object.
d = Dictionary$new()
value to the dictionary with key
key, potentially overwriting a
previously stored value.