1. One or more processor-accessible storage media comprising processor-executable instructions that, when executed by a processor, direct a computing device to perform actions comprising: retrieving one or more mapping descriptions from a runtime casting description, the one or more mapping descriptions defining feature-level mappings to create a casted object including casted features from a source object including source features independent of type information of the source object, wherein the features from the source object comprise a method feature or a property feature; casting a first object of a first type and a second object of a second type to a first casted object of a third type and to a second casted object of the third type, wherein the first type and the second type are different from the third type, wherein casting the first object of the first type to the first casted object of the third type includes casting a subset of features of the first object of the first type to the first casted object of the third type using the retrieved mapping descriptions from the runtime casting description, wherein the at least one of the features of the first casted object of the first type has a functionality different than a corresponding casted feature of the first casted object of the third type; wherein casting a second object of the second type to the second casted object of the third type includes casting a subset of features of the second object of the second type to the second casted object of the third type using the retrieved mapping descriptions from the runtime casting description; applying one or more algorithms to the first casted object of the third type and to the second casted object of the third type; detecting a change in the second casted object; propagating the change to the first casted object; and modifying the first object responsive to the change propagated to the first casted object in the propagating action.