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From: yms@beach.cis.ufl.edu (Yuh-Ming Shyy)
Newsgroups: comp.object
Subject: Infinite Loop of Message Passing
Message-ID: <26386@uflorida.cis.ufl.EDU>
Date: 18 Jan 91 20:08:28 GMT
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Reply-To: yms@beach.cis.ufl.edu ()
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Organization: UF CIS Department
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Hi, I just came across an interesting scenario about 
an infinite loop of message passing. Any opinion will 
be highly appreciated. 

The problem happens when we model each method as an 
individual object, say, as an instance of a class 
called "METHOD". We can then define some methods for 
METHOD such as "eval", "compile", etc. 

Now, suppose class "STUDENT" defines a method called 
"eval_GPA", and we send a message "eval_GPA()" to 
a student "s1". 

What happens now is interesting: object "s1" checkes 
that "eval_GPA" is a method defined by "STUDENT", and 
so it sends a message "eval()" to the object "eval_GPA". 

Object "eval_GPA" will then checks and finds that "eval" 
is a method defined by class "METHOD", so it sends a 
message "eval()" to the object "eval". 

Object "eval" will then checks and finds that "eval" is 
a method defined by class "METHOD", so it sends a 
message "eval()" to itself recursively. 

The message "eval()" will then be sent back and forth between 
"eval" and "METHOD" and nothing can be actually evaluated. 

I am sure there must be something wrong with the above scenirio, 
but theoritically I cannot find any error (if we model everything 
as object as many people claimed). 

Thanks. 

Yuh-Ming