Adds variables which can be referenced by upstream expressions and string substitutions.
Container for user-defined plugs. Nodes should never make their own plugs here, so users are free to do as they wish.
Turns the node on and off.
The variables to be added. Each variable is represented as a child plug, created either through the UI or using the CompoundDataPlug API.
An additional set of variables to be added. Arbitrary numbers of variables may be specified within a single IECore::CompoundData object, where each key/value pair in the object defines a variable. This is convenient when using an expression to define the variables and the variable count might be dynamic.
If the same variable is defined by both the variables and the extraVariables plugs, then the value from the extraVariables is taken.