Sorry I am lazy, I will copy paste a piece of a .tex


\section{Discovering used and unused classes}
There is some work that it is quite related to ImageSegment and it is used to discover used and unused classes.

There is a possibility to force a MethodDictionary fault with the message {\em ClassDescription>>induceMDFault}. This method copies the {\em methodDict} in the {\em organization} slot. Actually, it creates an Array with the {\em methodDict} and the {\em organization} and set it in the {\em organization} slot. Finally, it sets a {\em nil} to the {\em methodDict} instance variable. After this is done, when that class is used and the {\em methodDict} is asked\,---\,it is very important to acces the {\em methodDict} using the getter\,---\, it checks whether it is nil or not. If it is nil, it will search for that {\em methodDict} in the Array of the {\em organizaction} and it will then copy it to the {\em methodDict} instance variable.

Taking that explanation in mind, we can follow this three steps:

\begin{enumerate}
\item Send the message {\em ImageSegment>>discoverActiveClasses} which forces a MethodDictionary fault in all classes. Yes! It sends the message {\em induceMDFault} to all classes except classes like Array Object Class Message MethodDictionary. After this, all classes but those ones, will have the {\em methodDict} with {\em nil}.
\item Do a few things, use the system for a while. Maybe even save and resume the image.
\item Now, it is easy. All classes that still have a nil in the {\em mehodDict} is because they were not used, and those who have something different from {\em nil} is because they were. With the message {\em ImageSegment>>activeClasses} you can restore all remaining MethodDictionary faults and return the active classes. And with the message {\em ImageSegment>>swapOutInactiveClasses}� you can make up segments by grouping unused classes by system category and write them to disk.

A very important thing is that if you send the message {\em discoverActiveClasses}� you must then have to send the message {\em activeClasses} or {\em swapOutInactiveClasses}� because otherwise you will have a lot of classes with the {\em methodDict} in {\em nil}.

\end{enumerate}


is it clear ?

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