Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!asuvax!mcdphx!dover!digital!norm!shelley
From: shelley@atc.sps.mot.com (Norman K. Shelley)
Newsgroups: comp.lang.eiffel
Subject: Comments on proposed Eiffel language changes
Message-ID: <48a55876.12c9a@digital.sps.mot.com>
Date: 14 Feb 90 22:00:27 GMT
Sender: news@digital.sps.mot.com
Lines: 69

Comments on I.S.E.'s proposed changes for Eiffel 3.0 (14Feb90)

The new creation syntax and semantics looks very nice.

The demise of the special keywords - Clone, Forget, and Void - in favor of the
new syntax and semantics is welcomed.

"void references" problem:  The Void concept being replaced by the use of the
class NONE appears to be a very nice improvement.

The "improved syntax and semantics for the preconditions and postconditions" is
most welcomed. 

New feature:
As an addition for novice or unsuspecting programmers, it would be
useful when a
redefined routine trys to copy its parents pre or post condition if the
compiler
would warn the user of the redundancy.

Proposed variable argument enhancement.
> Many people do like, however, the flexibility of routines for which the
> number of arguments is not known in advance. Printing procedures are
> the classical example.
I must agree! An Eiffel variable argument mechanism  would be most useful.

> The mechanism may also be useful at the level of interfaces between
> Eiffel and other languages such as C and (some versions of) Fortran
> which support variable numbers of arguments; an example in C is
> printf.
Another example is SUN's "Xview" library which uses variable arguments heavily.

> Finally, although the default alphabet for identifiers is
> still the English letters plus digits and underscore, it becomes
> possible to use others if they are specified in a special file

New feature:
I would like to propose that the hyphen be added to the default alphabet for
identifiers and that the hyphen take over the accepted use of the
underscore for
separating words in an identifier.

Page 240 of "Eiffel: The Language" states that "internal upper-case letters ...
as in putAtRight, contradicts the standard conventions of English ...
and is not
part of the recommended style."  I agree BUT must note that the
underscore ('_')
as a word separator is NOT English either.  A whitespace is the accepted
standard but computers have troubles with whitespace in names/labels so what do
we do?  Common Lisp uses hypens ('-') as a separator and this has more
acceptance in English than an underscore.  So if we can't use blanks because of
computer limitation and internal upper-case because it does not match current
language conventions, then I think hyphens make MUCH more sense than
underscores
which themself do NOT conform to current language conventions.

-------------------------------------------------------------------------------
The reason for some qualified approvals is that until I can actually try
something I usually can not find the really deep problems that are hiding
beneath the surface.


Norman Shelley
Motorola - ATC
2200 W. Broadway AZ09/M350
Mesa, AZ 85202
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