Do I understand correctly that the main reason to use isMorph rather than is: Morph is that the former is faster. And is the reason to prefer is: Morph is that it is more robust against required changes in the code to accommodate other specific changes?

Wouldn't it be straightforward to use the is: * generic form and generate an automatic revision to the more specific form while providing a way to switch back whenever needed? Would such a system solve the problem discussed?

Offhand, optimizations for efficiency like this seem to me to be pretty easy to arrange and to undo with fairly simple "compilers". There are also tools which make creating such compilers quite easy. Here I think of a transformational attribute grammar (TAG) compiler which can create a working prototype language XX compiler in perhaps five times the volume of its Backus-Naur Form syntax.

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On 2008, Jan 25, , at 4:00, Michael Rueger m.rueger@acm.org wrote:

...

is: Class ^(self class) inheritsFrom: Class

isKindOf: already exists.

...

which would never have to be overridden? Obviously there are some is* methods that server a larger purpose but isn't more...polymorphic...to say

is* is much much faster

But, as I said, using is* is a sign of a design problem. If you use is* you are hardwiring the knowledge about certain classes into your architecture.