Fri Oct 14, 11:00-12:15, 4760 Boelter Hall

Practical Refactoring Tools Using Type Constraints

Frank Tip  
IBM T.J. Watson Research Center

Type constraints are a formalism for expressing relationships between the 
types of variables and expressions that must be satisfied in order for 
program constructs to be type-correct. Traditionally, type constraints have 
been used as the basis for type checking and type inference algorithms. 
In our work, we use type constraints to efficiently implement refactorings 
of object-oriented programs.  Refactorings are program transformations that 
are guided by the programmer and that aim at improving a program's design. 
Manually performing refactorings tends to be error-prone because checking 
the preconditions for a refactoring often involves non-local reasoning, and
tedious because a large number of source code modifications may be required. 
Hence, automated tool support is highly desirable. The main observation 
behind our research is the fact that many refactorings are concerned with 
the manipulation of class hierarchies and types, and that type constraints 
lend themselves naturally for the checking of preconditions and the 
computation of source code modifications. Using type constraints, have 
implemented several refactorings related to generalization (e.g., "Extract 
Interface", "Pull Up Members"), two refactorings associated with the 
migration to Java 1.5 generics ("Infer Generic Type Arguments", and 
"Introduce Type Parameter"), and a refactoring for the migration between 
library classes that are roughly functionally equivalent. The work has been 
implemented in Eclipse, and several of the presented refactorings are part 
of the standard Eclipse 3.1 distribution that can be downloaded from 
www.eclipse.org.  

This research is loosely based on papers published at OOPSLA'03, ECOOP'04, 
ECOOP'05, and OOPSLA'05, and on some work in progress. It is joint work 
with Dirk Baeumer, Ittai Balaban, Julian Dolby, Michael Ernst, 
Robert Fuhrer, Markus Keller, Adam Kiezun, and Bjorn De Sutter.

About the speaker:  Frank Tip received his Ph.D. from the University of 
Amsterdam in 1995.  Since then, he has worked at the IBM T.J. Watson 
Research Center in Hawthorne, NY, where he is currently manager of the 
"Program Analysis & Transformation" group.  Frank's current research 
interests include refactoring, analysis and optimization of object-oriented 
programs, change impact analysis, and the design of language features that 
make it easier to write race-free concurrent object-oriented programs. 
More information can be found at www.research.ibm.com/people/t/tip.

Hosts: Todd Millstein and Jens Palsberg