Look at the coverage browser developed by michel tilman:
http://users.pandora.be/michel.tilman/Smalltalk/


On Saturday, February 8, 2003, at 04:59 AM, Doug Clapp wrote:

> Given that Squeak is "reflective," would it be possible
> to write code such that...
>
> -- the system was "watched" as it was exercised, and...
>
> -- attention was paid to which "cases"  (ifTrue/ifFalse)
> were triggered more often, and...
>
> -- the methods were then re-written to have the "most
> likely (often)"if" be placed first in the method, to speed
> up the execution of "most often done things"?
>
> Obviously, this idea could be taken much further...
>
> doug clapp
>
>
Prof. Dr. Stéphane DUCASSE (ducasse at iam.unibe.ch) 
http://www.iam.unibe.ch/~ducasse/
  "if you knew today was your last day on earth, what would you do
  different? ... especially if, by doing something different, today
  might not be your last day on earth" Calvin&Hobbes