Abstract: The annotation of a returned reference from an executable component to signify that there are no external references to the particular object graph referenced by the returned reference. If either 1) there are no input arguments to the executable component or 2) each input argument is either immutable or represents an object graph that has no external mutable references pointing into the object graph, and no internal mutable references that reference external objects, the particular attribute is assigned to the returned reference. Accordingly, if the returned reference is writable (as determined by evaluating the declaration code or the call code for the executable component), the returned reference is free to have whatever access permissions assigned to it, and may also be assigned to an isolated memory location, though such assignments will cause the returned reference to lose the particular attribute.

Abstract: Handing errors in program execution. The method includes identifying a set including a plurality of explicitly identified failure conditions. The method further includes determining that one or more of the explicitly identified failure conditions has occurred. As a result, the method further includes halting a predetermined first execution scope of computing, and notifying another scope of computing of the failure condition. An alternative embodiment may be practiced in a computing environment, and includes a method handing errors. The method includes identifying a set including a plurality of explicitly identified failure conditions. The method further includes determining that an error condition has occurred that is not in the set including a plurality of explicitly identified failure conditions. As a result, the method further includes halting a predetermined first execution scope of computing, and notifying another scope of computing of the failure condition.

Abstract: The annotation of a returned reference from an executable component to signify that there are no external references to the particular object graph referenced by the returned reference. If either 1) there are no input arguments to the executable component or 2) each input argument is either immutable or represents an object graph that has no external mutable references pointing into the object graph, and no internal mutable references that reference external objects, the particular attribute is assigned to the returned reference. Accordingly, if the returned reference is writable (as determined by evaluating the declaration code or the call code for the executable component), the returned reference is free to have whatever access permissions assigned to it, and may also be assigned to an isolated memory location, though such assignments will cause the returned reference to lose the particular attribute.