"nil did not understand #selector" is great.

Similarly, "Instance of " can be replace by "a" as in
"aObject did not understand #selector"
"aReadWriteStream did not understand #selector"

For classes
"PragmaMenuBuilder class did not understand #selector"


Daniel Slomovits wrote:
I think it's because nil *is* pretty special--this is the equivalent of a NullPointerException or similar in other languages (even though in fact nil is an object like any other, it *is* usually a different type of *semantic* error on the part of the programmer than with any other class). UndefinedObject is also a pretty long class name, so it's nice to leave that out. But I would be all in favor of making it "nil did not understand #selector", to be more consistent but still concise.��

On Fri, Jun 27, 2025, 3:00���PM Aik-Siong Koh <askoh@askoh.com> wrote:
Why is UndefinedObject version of "did not understand" so different from
others?
It also inverts the object message paradigm.
Thanks
Aik-Siong Koh

description

������ ��"Returns a textual description of the exception (based on the
message instance variable). If message is nil, it returns the
defaultDescription instead."

������ ��message ifNil: [ ^ self defaultDescription ].
������ ��message lookupClass == UndefinedObject ifTrue: [
������ ������ ��^ message selector printString , ' was sent to nil' ].

������ ��^ 'Instance of ' , message lookupClass printString
������ ���� , ' did not understand ' , message selector printString