Am 21.01.2015 um 14:28 schrieb Paul Gilmartin:
On Wed, 21 Jan 2015 08:38:38 +0100, Bernd Oppolzer wrote:
It was the decision of the PL/1 language designers to make
the language more user friendly to the C community. You don't have to
use such language elements, if you don't like it. I see it this way:
PL/1 is such a powerful language, that it even allows different
programming styles. Or: why not allow language constructs, as long
as it is clear to the programmer, what the new language element does
and as long as the spirit of the language is not broken?
Are you saying that as an accommodation to C programmers PL/I
has recently provided pointers with types, with increments by element
size?
No, I don't think so.
I'm not aware of all the extensions to the PL/1 language of the last years;
there are some which I don't use like DEFINEd STRUCTURES, ORDINAL TYPEs
etc. ... mainly because the compatibility to the (long) existing
features is not so good,
IMHO. But pointers that increment in an other way than per address ... I
don't think
that that exists.
No, the things I had in mind was the assignments including increment etc,
the things like A += expression; etc ... works with other kinds of
operators, too,
of cours, not only addition. And that you can add an offset to a pointer
simply by
using the + sign. And, if C programmers want to use functions like
memset or
memcpy, they can, although there are other (PL/1) names for those functions
(PLIMOVE etc.).
BTW: variable ++; is not still possible in PL/1 for several good reasons.
I'm naive. What's a good reason (other than economy of language design)
for not providing "variable ++"? (And what of "++ variable"?) One
possibility might be lexical ambiguity.
Some speculation on my part:
in C, everything is an expression;
a ++ and ++ a are two very different expressions,
and this idea does not fit well into the PL/1 spirit.
The assignment a += 5;
in C is an expression, too (and may be assigned to other variables
and used, whereever expressions are allowed in C).
But it is no problem to take this kind of syntax over to PL/1,
WITHOUT assigning a value to the assignment A += 5;
(that is: without violating the language).
In PL/1:
A = B = C;
has a total different meaning than
a = b = c;
in C.
This has to do with:
In C, assignment and comparison are two different operators, = and ==,
but in PL/1, the same operator = is used for both.
Kind regards
Bernd
-- gill
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