Lukas Renggli writes:
 > > Now I was under the impression, that a context had a copy of a compiled
 > > method with copies of the literals, so that you could only modify the
 > > copies but not the literals in the compiled method. But it seems not to
 > > be that way:
 > 
 > This would turn a simple message send to be incredibly expensive.
 > 
 > > This is evil! :)
 > 
 > I want an immutability flag in the object-header!

It may be better to implement immutability inside the image using
immutable sub-classes and similar tricks to the write barriers for OO
DBs.

Doing so would allow the implementation to be optimised by all
optimisations that help for sends in general. Adding a immutability
flag would add another thing to check on every instance variable
write. Squeak's write barrier is expensive enough as it is.

Bryce