Method and mechanism for invocation on objects with interface inheritance

• US 6,412,019 B1
• Filed: 01/15/1997
• Issued: 06/25/2002
• Est. Priority Date: 09/19/1994
• Status: Expired due to Term

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Gibbons, Jonathan J., Kessler, Peter B., Radia, Sanjay R., Hamilton, Graham, Powell, Michael L.
• Primary Examiner(s): Courtenay, III, St. John
• Assistant Examiner(s): LAO, SUE X
• Application Number:
  US08/783,913
• Time in Patent Office: 1,987 Days
• Field of Search: 709/303, 709/315, 709/316, 395/705, 395/701, 717/5, 717/1, 717/100, 717/116, 707/103, 707/103.R, 707/103.Y, 707/103.Z
• US Class Current: 719/315
• CPC Class Codes: G06F 9/449 Object-oriented method invocation or resolution

Abstract

Methods and apparatus in an object oriented programming environment for invocation of objects with interface inheritance. An object reference using mtables contains two parts, more specifically, a pointer to the data for an object and a pointer to the methods on the object. The methods on the object are represented by a collection of mtables. An mtable for a given interface consists of pointers to mtables for inherited interfaces and pointers to functions implementing the operations declared in the interface. An mtable pointer in an object reference points to an mtable for an apparent interface of the object reference. Mtables for any inherited interfaces are reached by indirection from the mtables for the apparent interface.

Claims

1. A computer implemented method for invocation of operations on objects with interface inheritance in an object oriented programming environment on a data processor containing memory, in which a plurality of objects are categorized into classes according to related operations, said method comprising:

creating an mtable for an apparent interface for an object, the mtable including a plurality of pointers to functions for said interface and a plurality of pointers to additional mtables, said additional mtables being for a plurality of inherited interfaces of said object and having the same table structure as said mtable for said apparent interface;

providing an identifier field including identifier information for said mtable contained within said mtable;

providing a first count field identifying a numerical count of said plurality of pointers to functions contained within said mtable;

providing a second count field identifying a numerical count of said plurality of pointers to additional mtables contained within said table;

pointing to data for said object using a pointer, said pointer being part of an object reference, said data for said object being separate from said object reference;

pointing to said mtable for said object using a pointer, said pointer being part of said object reference, said pointing to data and said pointing to said mtable being facilitated by said object reference using separate pointers; and

invoking a plurality of operations on said data and said mtable pointed to by said object reference.

2. The method of claim 1, further comprising representing mtables into operations per interface, said mtables having pointers to said operations, and pointers to base mtables, said pointers representing interface inheritance.

3. The method of claim 1, further comprising representing said operations on said object by a collection of mtables.

4. The method of claim 1 wherein said plurality of pointers to functions, point to functions implementing operations declared in said interfaces.

5. The method of claim 1, further comprising representing separate graphs of mtables for different implementations of operations.

6. The method of claim 1, further comprising sharing mtables among classes for a common implementation of operations.

7. The method of claim 1, further comprising sharing all mtables when implementations are remote procedure call stubs in a distributed object-oriented system using an interface definition language which supports interface inheritance.

8. An apparatus for invocation of operations on objects with interface inheritance in an object oriented programming environment on a data processor containing memory, in which a plurality of objects are categorized into classes according to related operations, said apparatus comprising:

a plurality of mtables, one being for an apparent interface for an object, the mtable including a plurality of pointers to functions for said interface, and a plurality of pointers to additional mtables, said additional mtables being for a plurality of inherited interfaces of said object and having the same table structure as said mtable for said apparent interface, said separate pointer and said table structure allowing for more efficient handling of the invocation of operation on said object with said plurality of inherited interfaces;

an identifier field including identifier information for said mtable contained within said mtable;

a first count field identifying a numerical count of said plurality of pointers to functions contained within said mtable;

a second count field identifying a numerical count of said plurality of pointers to additional mtables contained within said table;

a pointer to data for said object, said pointer being part of an object reference, said data for said object being separate from said object reference;

a pointer to said mtable for said object, said pointer being part of said object reference, said pointer to said data and said pointer to said mtable facilitated by said object reference using separate pointers; and

circuitry invoking a plurality of operations on said data and said plurality of mtables pointed to by said object reference.

9. The apparatus of claim 8 further comprising a representation of the collection of mtables for said operations on said object.

10. The apparatus of claim 8 wherein said functions implementing an operation declared in said interfaces.

11. The apparatus of claim 8, further comprising a representation of mtables, one mtable per class of object, said mtables having pointers to operations, and pointers to mtables, said pointers representing interface inheritance.

12. The apparatus of claim 11, further comprising a representation of separate graphs of mtables for different implementations of operations.

13. The apparatus of claim 12, further comprising shared mtables, said shared mtables shared among classes for a common implementation of operations.

14. The apparatus of claim 13, wherein said shared mtables are shared when said implementations are remote procedure call stubs in a distributed object-oriented system using an interface definition language which supports interface inheritance.

15. A computer system for invocation of operations on objects with interface inheritance in an object oriented programming environment on a data processor containing memory, in which a plurality of objects are categorized into classes according to related operations, said system comprising:

a plurality of mtables, one being for an apparent interface for an object, the mtables having a table structure including an identifier of said interface, a plurality of pointers to functions for said interface, and a plurality of pointers to additional mtables, said additional mtables being for a plurality of inherited interfaces of said object and having the same table structure as said mtable for said apparent interface, said separate pointer and said table structure allowing for more efficient handling of the invocation of operation on said object with said plurality of inherited interfaces;

an identifier field including identifier information for said mtable contained within said mtable;

a first count field identifying a numerical count of said plurality of pointers to functions contained within said mtable;

a second count field identifying a numerical count of said plurality of pointers to additional mtables contained within said table;

a pointer to data for said object, said pointer being part of an object reference, said data for said object being separate from said object reference;

a pointer to said mtable for said object, said pointer being part of said object reference, said pointer to said data and said pointer to said mtable facilitated by said object reference using separate pointers;

circuitry invoking a plurality of operations on said data and said plurality of mtables pointed to by said object reference; and

a compiler for generating said plurality of mtables.

16. The computer system of claim 15, further comprising a representation of the collection of mtables for said operations on said object.

17. The computer system of claim 15 wherein said functions implement operations declared in said interfaces.

18. The computer system of claim 15, further comprising a representation of mtables, one mtable per class of object, said mtables having pointers to said operations, and pointers to mtables, said pointers representing interface inheritance.

19. The computer system of claim 18, further comprising a representation of the separate graphs of mtables for different implementations of operations.

20. The computer system of claim 18, further comprising shared mtables, said shared mtables shared among classes for a common implementation of operations.

21. The computer system of claim 20, wherein said shared mtables are shared when said implementations are remote procedure call stubs in a distributed object-oriented system using an interface definition language which supports interface inheritance.