At 7:29 Uhr -0800 30.03.1999, Dan Ingalls wrote:

...

123 size no longer responds with 0. nil size no longer responds with 0.

Why ?

I found the latter extremely handy in cases where one could get back either a (possibly empty) collection or nil.

I agree with the why question. Many collections are lazy initialized and that makes nil size really useful. Moreover, size is a basic message; one expects that any object can nicely respond to it.

Leandro