Non-forgeable objects in an object system
AssigneeElectronic Data Systems Corporation
InventorsRichard M. Cohen, William H. Vollers
Life of this patent
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Abstract
A method, system, and computer program product for defining a non-forgeable object is provided. In one embodiment, a non-forgeable object class is defined to include an attribute slot that can be set by an approved factory. The non-forgeable object class is further defined to include a predicate method that is satisfied only if the attribute slot has been set by an approved factory.
Claims18
A method for defining a non-forgeable object comprising:
- defining an approved factory to define a non-forgeable object class to include a marker attribute slot restricted to holding marker type values by accessing the controls of the programming system;
- restricting the marker attribute slot so that it is not directly visible to other classes such that the contents of the marker slot may not be extracted from an instance of the object;
- and
- defining the non-forgeable object class to include a predicate method that is satisfied only if the attribute slot has been set by an approved factory;wherein only approved factories may pass nonnull marker instances to a setter method of the non-forgeable object.
A computer program product in a computer readable storage media for use in a data processing system for defining a non-forgeable object comprising:
- first instructions for defining an approved factory to define a non-forgeable object class to include a marker attribute slot restricted to holding marker type values by accessing the controls of the programming system;
- second instructions for restricting the marker attribute slot so that it is not directly visible to other classes such that the contents of the marker slot may not be extracted from an instance of the object;
- and
- third instructions for defining the non-forgeable object class to include a predicate method that is satisfied only if the attribute slot has been set by an approved factory;
- wherein only approved factories may pass non-null marker instances to a setter method of the non-forgeable object.
A system for defining a non-forgeable object comprising:
- first means for defining an approved factory to define a non-forgeable object class to include a marker attribute slot restricted to holding marker type values by accessing the controls of the programming system;
- second means for restricting the marker attribute slot so that it is not directly visible to other classes such that the contents of the marker slot may not be extracted from an instance of the object;
- and
- third means for defining the non-forgeable object class to include a predicate method that is satisfied only if the attribute slot has been set by an approved factory;
- wherein only approved factories may pass non-null marker instances to a setter method of the non-forgeable object.
Dependencies are inferred from the claim text.