Linktime recognition of alternative implementations ofprogrammed functionality

• US 20030046673A1
• Filed: 06/29/2001
• Published: 03/06/2003
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Terry, Donn S., Zions, Jason D., Copeland, Jeffrey L.
• Granted Patent: US 7,757,225 B2
• Time in Patent Office: Days
• US Class Current: 717/163
• CPC Class Codes: G06F 8/443 Optimisation
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading

Abstract

A method and apparatus are disclosed for optimizing the runtime behavior of database or other applications by allowing selection of alternative code segments during linking of pre-compiled object modules. A macro-preprocessor inserts a declaration for a global variable in the source code in response to an occurrence of a command of interest. The linker selects object modules for executing other commands based on the presence or absence of the declaration for the global variable in the preprocessed source code. The method and apparatus are useful in implementing programming language statements including non-procedural programming languages such as the Embedded Structured Query Language (ESQL).

Claims

1. A method of generating an executable from a computer program having a plurality of statements in a source code, the method comprising the steps of:

inserting, by a macro-preprocessor, a declaration statement for a first variable in a first source file in the computer program in response to detecting a first statement thereby rendering a modified first source file;

compiling the modified first source file to generate a first object module;

linking the first object module to generate an executable program, the linking step including resolving the first variable by linking a second object module having a definition corresponding to the first variable; and

providing a third object module in a linker library, the third object module corresponding to a second statement and including code supporting the first statement.

2. The method of claim 1, wherein the computer program includes statements conforming to a non-procedural programming language.

3. The method of claim 2, wherein the computer program is created using at least one statement conforming to an embedded structured query language.

4. The method of claim 1, wherein the first variable declaration excludes a definition for the first variable.

5. The method of claim 1, wherein the code to support the first statement in the third object module includes instructions to carry out additional tasks required by the first statement when implementing the second statement.

6. The method of claim 5, wherein the code to support the first statement is accessed in the third object module from the second object module.

7. The method of claim 2, wherein an additional non-procedural programming language is used to provide a third statement conforming to the additional non-procedural programming language, wherein in response to detecting the third statement a second variable is declared in at least one source file in the computer program.

8. The method of claim 1 wherein the macro-preprocessor does not declare the first variable in the modified first source file if the macro-preprocessor does not detect the first statement in the first source file whereby the first object module is not linked with the second object module.

9. The method of claim 7, wherein a fourth object module having a definition for the second variable is linked instead of the second object module.

10. A computer-readable medium having computer executable instructions for performing the steps of a method of generating an executable from a computer program having a plurality of statements in a source code, the method comprising the steps of:

inserting, by a macro-preprocessor, a declaration statement for a first variable in a first source file in the computer program in response to detecting a first statement thereby rendering a modified first source file;

compiling the modified first source file to generate a first object module;

linking the first object module to generate an executable program, the linking step including resolving the first variable by linking a second object module having a definition corresponding to the first variable; and

providing a third object module in a linker library, the third object module corresponding to a second statement and including code supporting the first statement.

11. A computer-readable medium as in claim 10, wherein the computer program includes statements conforming to a non-procedural programming language.

12. A computer-readable medium as in claim 11 having computer executable instructions in the computer program conforming to an embedded structured query language.

13. A computer-readable medium as in claim 10, wherein the code to support the first statement in the third object module includes instructions to carry out additional tasks required by the first statement when implementing the second statement.

14. A computer-readable medium as in claim 13, wherein the code to support the first statement is accessed in the third object module from the second object module.

15. A computer-readable medium as in claim 11, wherein an additional non-procedural programming language is used to provide a third statement conforming to the additional non-procedural programming language, wherein responsive to detection of the third statement a second variable is declared in at least one source file in the computer program.

16. A computer-readable medium as in claim 10, wherein the macro-preprocessor does not declare the first variable in the modified first source file if the macro-preprocessor does not detect the first statement in the first source file whereby the first object module is not linked with the second object module.

17. A computer-readable medium as in claim 15, wherein a fourth object module having a definition for the second variable is linked instead of the second object module.

18. A linker library for generating an executable by a linker linking compiled object modules, the linker library comprising a first object module having a definition for a first variable providing a first value to the first variable and a declaration and definition for a second variable providing a second value to the second variable whereby a second object module can test, at runtime, the second variable for the second value to determine if the first object module is linked by the linker into the executable.

19. The linker library of claim 18 wherein the linker library has only one object module.

20. The linker library of claim 18 further having a third object module after the first object module, the third object module having another declaration and definition for the second variable providing a third value to the second variable.

21. The linker library of claim 20 wherein the third object module is the last object module in the linker library.

22. A linker library comprising a last object module having a definition for a variable, the last object module following at least one object module in the linker library wherein the variable is declared in at least one object module distinct from the last object module.

23. A macro-preprocessor for preprocessing program source code, the program source code comprising programming language statements such that an implementation of a first statement requires changing an implementation of a second programming language, wherein the macro-preprocessor introduces a declaration for a first variable in a preprocessed program source code in response to detecting an occurrence of the first programming statement in the program source code.

24. The macro-processor of claim 23 wherein the programming language is a non-procedural programming language.