Re: "WITH Considered Dangerous" by Wirth?

thutt@clark.net (Taylor Hutt)
Sun, 26 Jun 1994 20:24:04 GMT

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"WITH Considered Dangerous" by Wirth? Paul_Long@ortel.org (1994-06-25)
re: "WITH Considered Dangerous" by Wirth? jkahrs@mailserv.zdv.uni-tuebingen.de (1994-06-26)
Re: "WITH Considered Dangerous" by Wirth? thutt@clark.net (1994-06-26)
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Newsgroups: comp.compilers,comp.lang.oberon
From: thutt@clark.net (Taylor Hutt)
Keywords: Pascal, modula, design
Organization: Society for People Who Believe All Shampoos are the Same
References: 94-06-182 94-06-194
Date: Sun, 26 Jun 1994 20:24:04 GMT

Paul_Long@ortel.org (Paul Long) writes:
>What Wirth languages do not have a WITH statement? Oberon?


<jkahrs@mailserv.zdv.uni-tuebingen.de> wrote:
>Oberon HAS a WITH statement, but its semantics is different (OOP).
>BTW: Another thing Wirth did not include in Oberon is the FOR statement,
>subrange types, enumerations and array indices starting at an arbitrary value.


More specifically, Oberon's WITH statement is a regional type-guard used
to change the dynamic type of a variable to that of an extended type at
runtime.


In Oberon-2 (which is not strictly a Wirth language), the syntax of the
WITH statement has changed (in a downwardly compatbile way) to allow a
CASE-like approach to the regional type-guard.


While it is true that FOR was removed from Oberon, it was reintroduced in
Oberon-2, and a few Oberon-1 compilers from ETH also support the FOR loop.


For more information please refer to comp.lang.oberon or to the anon ftp
server neptune.inf.ethz.ch.


Taylor Hutt
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