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From: johnmark@Neon.Stanford.EDU (John M. Agosta)
Newsgroups: comp.sys.mac.programmer
Subject: new() type checking in Object languages
Keywords: OOPS
Message-ID: <11615@polya.Stanford.EDU>
Date: 31 Aug 89 20:18:23 GMT
References: <4590@portia.Stanford.EDU>
Sender: USENET News System <news@Polya.Stanford.EDU>
Reply-To: johnmark@Neon.Stanford.EDU (John M. Agosta)
Organization: Stanford University, Computer Science Dept.
Lines: 16
cc: duggie@Jessica

duggie@Jessica.stanford.edu (Doug Felt) writes:


> I believe Object Pascal restricts assignments in one direction but not
> the other.  I am not sure but I think the assignment is a runtime
> restriction, in that code is generated to check the class of the
> object being assigned and test this against the class of the variable.

Yes, in MacApp beta9 the assignment coercion is checked by code at
runtime. This appears to be different than previous versions, 
coercions that I ported over to beta9 now break into the debugger
with a coercion error message. Apparently the debug versions of MacApp
applications do significant amount of runtime checking of a host of
errors that were not examined before.

-johnmark