Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!hub!eiffel!bertrand
From: bertrand@eiffel.UUCP (Bertrand Meyer)
Newsgroups: comp.lang.eiffel
Subject: Re: JOOP letter on Eiffel type checking
Message-ID: <255@eiffel.UUCP>
Date: 24 Feb 90 20:20:50 GMT
References: <2829@umbc3.UMBC.EDU>
Distribution: comp.lang.eiffel
Organization: Interactive Software Engineering, Santa Barbara CA
Lines: 12

From <2829@umbc3.UMBC.EDU> by bruce@menkar.gsfc.nasa.gov
(Bruce Mount 572-8408):

> In the current JOOP (Jan/Feb 1990, page 10), Hans-Stephan Jansohn questions 
> the type-checking ability of Eiffel in a detailed letter to the editor.

The matter at hand (on which I receive about two letters a week
reporting it as a newly discovered problem) was discussed in
excruciating detail long ago. Please see <176@eiffel.UUCP>
and <177@eiffel.UUCP>, a two-part article posted on July 10,
1989 in this newsgroup.

Briefly:

	- No other policy than the Eiffel one is possible to write
	realistic object-oriented software (as opposed to toy
	examples).

	- The question was addressed too summarily in my book
	``Object-Oriented Software Construction''. The topic of the
	book was the method, however, not the language per se,
	which is covered by ``Eiffel: The Language'', currently
	a manual available from Interactive.

	- The current Eiffel implementation misses some erroneous
	cases which are easy to concoct in artificial examples but
	seldom arise in practice. (I cannot recall a single
	example in our own experience of writing hundreds of
	thousands of lines of Eiffel.)

	- The strategy for dealing with these cases was outlined in
	the net article mentioned above. It will be implemented
	as part of Interactive's version 3 of Eiffel.


-- Bertrand Meyer
bertrand@eiffel.com