From mboxrd@z Thu Jan  1 00:00:00 1970
From: ron@ronnatalie.com (Ron Natalie)
Date: Fri, 12 May 2017 22:45:02 -0400
Subject: [TUHS] C declarations.
In-Reply-To: <20170513012415.GZ4341@mcvoy.com>
References: <015401d2caa0$79762650$6c6272f0$@ronnatalie.com>
 <68E8DC0A-D1B8-4FF0-AD26-ACDC57E308AF@pobox.com>
 <20170511223232.GM4341@mcvoy.com>
 <015b01d2caa7$c658c020$530a4060$@ronnatalie.com>
 <20170513012415.GZ4341@mcvoy.com>
Message-ID: <025701d2cb92$ec8182a0$c58487e0$@ronnatalie.com>

There's no performance "hit" because it doesn't work now.    There's really
no difference performance or computational complexity wise for

char x[4], y[4];
x = y;
and
struct { char a[4]; } x, y;
x = y;

About the only thing it would have broken (and would still break today), is
the fact that function parameters that are defined to be arrays, really pass
pointers.

char x[4];
void foo(char a[4]);
foo(x);

would be costlier than it is now doing the pass by value.    Of course you
could always fudge if you wanted to pass the pointer by actually doing it
that way...
char x[4]
void foo(char *a);
foo(x);

-----Original Message-----
From: Larry McVoy [mailto:lm@mcvoy.com] 
Sent: Friday, May 12, 2017 9:24 PM
To: Ron Natalie
Cc: 'Larry McVoy'; 'David Arnold'; 'The Eunuchs Hysterical Society'
Subject: Re: [TUHS] C declarations.

On Thu, May 11, 2017 at 06:41:47PM -0400, Ron Natalie wrote:
> If had my way, y = x and passing and returning arrays by value would 
> work just like every other C type.

Maybe, just maybe, now that makes sense.  But even now that would be a perf
hit unless you added some magical copy on write semantics like Tcl has so it
can have pass by value semantics but pass by reference performance.

Back then, I think the perf hit would have been so bad everyone would be
passing arrays as a reference anyway.
--
---
Larry McVoy            	     lm at mcvoy.com
http://www.mcvoy.com/lm