Computer system, virtual machine, runtime representation of object, storage media and program transmission apparatus

A virtual machine that executes a program described in an object-oriented programming language on a computer system, comprising:

• an object, a type information block, and a class structure as runtime representation for an object in the object-oriented programming language,
• the object having a header including a pointer to the type information block and data itself,
• the type information block having a class pointer pointing to the class structure and a virtual method table,
• a plurality of class pointers are provided depending on the number of states of the object to be represented and individual class pointers are associated with individual states of the object,
• wherein the pointer included in the header of the object uses lower bits of the pointer to point to the class pointers individually in order to represent the states of the object, said virtual machine changing a value of said pointer so that an efficient runtime representation of an object's state using one of said plurality of class pointers in said type information block is available when executing in said virtual machine.

A method for runtime representation of an object described in an object-oriented programming language when executing the object on a computer system that implements the object-oriented programming language, comprises

• an object, a type information block having a plurality of class pointers corresponding to the states of the object, and a class structure pointed by the class pointers;
• wherein the number of class pointers is 2m and the size of the class pointers is 2n bytes, and
• allocating the type information block so that (m+n) lower bits of a pointer included in a header of the object be (2(m+n)−1)−(2n−1) when the pointer points to the class pointer at the highest address in the type information block, then allocating 2m class pointers in multilevel toward a lower address from the class pointer pointed by said pointer, and,
• setting a value of said pointer so that an efficient runtime representation of an object's state using one of said 2m class pointers in said the information block is available when executing in said computer system.

A storage media for storing a program that is readable by input means of a computer, comprising a software product implementing a processing system for an object-oriented programming language,

• wherein an object, a type information block, and a class structure are provided as runtime representation of the object in the object-oriented programming language that is implemented in the computer,
• the object having a header including a pointer to the type information block and data itself,
• the type information block having class pointers pointing to the class structure and a virtual method table,
• the class pointers are provided in multilevel depending on the number of states of the object to be represented and individual class pointers are associated with individual states of the object,
• wherein the pointer included in the header of the object uses lower bits of the pointer to point to the class pointers individually in order to represent the states of the object, said computer changing a value of said pointer so that an efficient runtime representation of an object's state using one of said class pointers in said type information block is available when executing in said virtual machine.

A program transmission apparatus, comprising:

• a storage means for storing a software product implementing a processing system for an object-oriented programming language,
• wherein an object, a type information block, and a class structure are provided as runtime representation of the object in the object-oriented programming language that is implemented in the computer,
• the object having a header including a pointer to the type information block and data itself,
• the type information block having class pointers pointing to the class structure and a virtual method table,
• the class pointers of the type information block are provided in multilevel depending on the number of states of the object to be represented and individual class pointers are associated with individual states of the object,
• wherein the pointer included in the header of the object uses lower bits of the pointer to point to the class pointers individually in order to represent the states of the object;
• and
• a transmission means for reading a program from the storage means and transmitting the program.