Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!bony1!richieb
From: richieb@bony1.uucp (Richard Bielak)
Newsgroups: comp.object
Subject: Re: Do we really need types in OOPL's?
Message-ID: <1990Oct10.141900.26769@bony1.uucp>
Date: 10 Oct 90 14:19:00 GMT
References: <0yw10qr@Unify.Com> <411@eiffel.UUCP> <736@tetrauk.UUCP> <CLINE.90Oct4111329@cheetah.ece.clarkson.edu> <1990Oct5.013201.12459@cbnewsc.att.com>
Reply-To: richieb@bony1.UUCP (Richard Bielak)
Organization: Bank of New York
Lines: 36

In article <1990Oct5.013201.12459@cbnewsc.att.com> lgm@cbnewsc.att.com (lawrence.g.mayka) writes:
[..lots of stuff left out..]
>
>I encourage those who claim that dynamic typing is "the wrong choice"
>for large software systems to actually run experiments on large (e.g.,
>over a million lines of source) software systems, comparing dynamic
>vs. static typing - above all, for ease of modification and extension.
>

I agree with Lawrence that static typic is no enough in any large
software system. However, we should look at static and dynamic typing
as complementary. One does not elimite the need for the other. 

Type checking at compile time protects the programmer from a lot of
stupid mistakes. For example, passing the right number and right type
of parameters to a routine.

At runtime, dynamic checking catches errors that could not be detected
at compile time. For example, checking array bounds in PASCAL.

IMHO an "industrial strength" language should provide both static and
dynamic checking. Since it is really *impossible* to write completely
correct software, we should at least be able to detect errors then they
happen. That's how its done in hardware. People don't publish proofs
that the memory chips are correct. Instead they provide facilities to
dectect errors, in case cosmic rays flipped some bits.


...richie


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