JEqualityGen: Generating Equality and Hashing Methods

Grech, Neville, Fischer, Bernd and Rathke, Julian (2010) JEqualityGen: Generating Equality and Hashing Methods At Generative Programming and Component Engineering,, Netherlands. 10 - 13 Oct 2010. , pp. 177-186.


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Manually implementing equals (for object comparisons) and hashCode (for object hashing) methods in large software projects is tedious and error-prone. This is due to many special cases, such as field shadowing, comparison between different types, or cyclic object graphs. Here, we present JEqualityGen, a source code generator that automatically derives implementations of these methods. JEqualityGen proceeds in two states: it first uses source code reflection in MetaAspectJ to generate aspects that contain the method implementations, before it uses weaving on the bytecode level to insert these into the target application. JEqualityGen generates not only correct, but efficient source code that on a typical large-scale Java application exhibits a performance improvement of more than two orders of magnitude in the equality operations generated, compared to an existing system based on runtime reflection. JEqualityGen achieves this by generating runtime profiling code that collects data. This enables it to generate optimised method implementations in a second round.

Item Type: Conference or Workshop Item (Other)
Additional Information: Event Dates: October 10-13, 2010
Venue - Dates: Generative Programming and Component Engineering,, Netherlands, 2010-10-10 - 2010-10-13
Keywords: meta-programming, equality, hashing, code generation, Java, Scala, AspectJ, AOP
Organisations: Electronic & Software Systems
ePrint ID: 271893
Date :
Date Event
10 October 2010Published
Date Deposited: 11 Jan 2011 13:09
Last Modified: 17 Apr 2017 18:04
Further Information:Google Scholar

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