Standard C Digest - V1 #2

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**************** mod.std.c  Vol. 1 No. 2  11/4/84 ********************

Today's Topic:
	Comments on the addition of aggregate constants to C...  (2)

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Date: Fri, 2 Nov 84 23:59:34 -0100
From: mcvax!guido (Guido van Rossum)
Subject: Re: aggregate constants

In article <464 at homxa.UUCP> hpdsa!decot (Dave Decot) proposes to add
aggregates to the language.  My opinion: might be a good idea, but...

It is very unorthogonal that aggregates must contain only constants.
The old rule is:

			static:                         auto:

can be
    initiated with:     constant expr                   any expression
and with:               constant aggregate              ---

I think that the empty space should be filled, if at all, with
"any aggregate", and not with "constant aggregate".  After all,
the ambiguities that are caused because braces are used both for
compound statements and for aggregates, could hardly become worse
when aggregates are allowed to contain variable expressions.
The semantics cannot be a problem either.  The order of evaluation
can be left unspecified (as with argument lists and operands of
binary and ternary operators).

>           Even if the type is 'pointer to char', the string pointed to by
>    that part of the initial value is the same each time it is executed,
>    and is not affected by changes to previous instances of the string.
>    ... [implementation proposal] ...

This makes only sense if the same requirement is made for the use
of constant strings in general.  I prefer having all strings read-only,
which is in accordance with decent usage and fair expectation.
--
	Guido van Rossum, "Stamp Out BASIC" Committee, CWI, Amsterdam
	guido at mcvax.UUCP
"The number of arguments is important unless some of them are correct."
----------------------------------------------------------------------

Date: 4 Nov 84 00:49:58 CST (Sun)
From: utzoo!henry
Subject: Re: Array proposals

References: <464 at homxa.UUCP>

> Proposal to add aggregate constants to C.  Proposals to add array lvalues,
> assignment, comparison, parameters, and return values to C.	
> ...

Has any of this been implemented anywhere?  With what results?  What were
the problems (both for the implementor and the customers)?  How much use
was made of the features?  Did it break any existing programs?  Did it
result in significant improvements in efficiency or readability in a
significant number of programs?

If the answer to the first question is "no", then why is this being
suggested as part of the standardization of an existing language?

				"The only way to truly understand a
				 feature is to implement it."
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry
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End of Vol. 1, No. 2. Std-C  (Nov. 4, 1984  07:00:00)
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