Common UPS variable and generic variable datatypes

[gbakeman]

NUTVariable

A variable that tries to closely represent the behavior of a state (variable) in the C-based NUT server and client code represents it. This will be largely abstracted from the consumer of this library by way of providing a higher-level object.

UPSVariable

Wraps a NUTVariable. Takes in update commands & information from a managing object, and allows read access to the consumer. Allows and handles updates from the consumer depending on variable properties. May also keep a history of read values and interactions with the NUT server.

CommonUPSProperty

Represents a common property of a UPS that someone may expect, such as Name and Description, as well as technical indicators like input and output values, and line and battery properties. These in turn may be directly represented by an underlying UPSVariable, or involve an algorithm by calculating it from some combination of known UPSVariables. What method or mode of providing this property should be indicated, or if it is even available at all.