Re: Smaller C

From	"Rod Pemberton" <boo@fasdfrewar.cdm>
Newsgroups	alt.os.development
Subject	Re: Smaller C
Date	2015-09-13 03:45 -0400
Organization	Aioe.org NNTP Server
Message-ID	<op.x4v45jxsyfako5@localhost> (permalink)
References	(15 earlier) <mssfjm$e3$1@speranza.aioe.org> <a9110bdf-add3-428c-b6da-2dbd52f45557@googlegroups.com> <msvds4$ig1$1@speranza.aioe.org> <op.x4tlsdpnyfako5@localhost> <mt109k$kje$1@dont-email.me>

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On Sat, 12 Sep 2015 06:56:36 -0400, James Harris <james.harris.1@gmail.com> wrote:

> "Rod Pemberton" <boo@fasdfrewar.cdm> wrote in message
> news:op.x4tlsdpnyfako5@localhost...
>> On Fri, 11 Sep 2015 16:32:14 -0400, Benjamin David Lunt
>> <zfysz@fysnet.net> wrote:

>>> However, at the moment, and probably for some time, I will not
>>> need anything like that in my OS development, and will probably
>>> not pursue it much further than what I have done so far.  At
>>> least not at the moment.  I will be interested to see what you
>>> come up with, whenever you do add this functionality to yours.
>>
>> Well, I rarely use any qualifiers.  They're generally not needed,
>> if you're a cautious programmer.  I've never found a use for 'const'.
>
> I don't use it much but const is a good way to confirm that a certain
> piece of data is not updated in a function.

C supports pass-by-value by default and pass-by-reference via a pointer.
Just how do you modify a value passed-by-value? ...

> Whether you are a cautious
> programmer or not, if you look at a certain function and wonder whether
> a variable, say, is updated anywhere in the function const can confirm
> it without you having to read through and understand the entire function
> (as long as it's not pointed at!).

When would you need that?

I can understand the compiler being able to optimize better if
it's present, but I personally have never had a need for that
with my code or someone else's.

>> I've only used 'static' once for convenience.
>
> C's static can be very useful in compartmentalising code. IIRC from
> discussions we've had before I know you don't favour data hiding so
> it's not surprising that it's not one you use much.

I use what's appropriate (IMO) for the code.  Programming is complicated
enough without making a mess of it.  Extra qualifiers, which most
programmers have difficulty understanding and using correctly, is one
such example.  How many times have you had to fix C code that had
incorrect 'const' and 'static' plastered everywhere?

> In a function static says, essentially, to place the declaree in the
> data section (yet only visible in this function) rather than in the
> function's activation record.

Deja Vu!

Now, technically, C doesn't require an activation record, so
to be proper ...

s/function's activation record/auto storage/

[Sigh, this should really remind you of what I just said to Alexei ...]

AFAIR, C doesn't have any "activation records".  So, what is a
"function's activation record"?  Google says an "activation
record" is the same as a "stack frame".  Deja Vu again!  I'd
swear I posted a similar response in the past ...  Hence, the same
comment as was said to Alexei, but modified for you.  You've used
this term before.  Does this term come from your IBM mainframe
background that you "cut [your] teeth on"? ...  Upon?

That aside.  Yes, use of 'static' on a variable limits usage, i.e.,
scope, to that procedure.  Although, the data is preserved across
procedure calls, just like a file scope variable, instead of being
created and destroyed like a procedure 'auto' variable.  So what
real advantage does a 'static' variable have over a file scope
variable?  (rhetorical, i.e., I think the answer is: 'none'.)
Unfortunately, the 'static' keyword has at least four other uses,
two of which have to do with linking.  That opens up the opportunity
for misuse and errors of the keyword 'static', which can be avoided
by simply not using 'static'.

> Outside a function static says to keep the declaree private and
> not share it with other source files. IME that can be useful
> for variables and functions.

If the other source files are "unaware" of the variable, because
the programmer did not declare said variable as an 'extern' in the
other source files, how would the source file "know" of said variable?
...

>> 'register' was convenient.
>
> I haven't used register for many years. It was useful once, when
> compilers were not smart enough to do sensible register allocation but
> it more often would get in the compiler's way now. The only use for it I
> can think of these days is to tell the compiler that a certain value
> must not have its address taken, and that doesn't seem very useful.
>

If you're coding an interpreter, you'll have a bunch of address
pointers to implement the virtual machine's interpreter.  The
interpreter is likely to be implemented in multiple parts as
multiple functions of form 'void func(void)', which means you'd
have to have said pointers as file scope and should prefer that
they are truly 'register'.  C doesn't support nested functions
which could've been used to make the code cleaner, if available.

Rod Pemberton

-- 
Just how many texting and calendar apps does humanity need?

Thread

Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-07-11 20:39 -0700
  Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-12 04:24 -0400
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-07-12 03:17 -0700
      Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-13 03:28 -0400
    Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-07-12 19:12 +0100
      Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-07-12 17:09 -0700
      Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-07-13 11:10 +0100
        Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-13 23:13 -0400
          Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-07-14 09:08 +0100
            Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-15 02:23 -0400
  Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-08-15 02:12 -0700
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-06 15:54 -0700
      Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-07 12:19 -0700
        Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-07 13:30 -0700
          Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-09 19:38 -0700
            Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-09 19:49 -0700
            Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-09 20:58 -0700
            Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-10 01:45 -0700
              Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-10 10:45 -0700
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-10 23:20 -0700
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-11 09:26 +0200
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-11 09:50 +0200
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-11 00:58 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 17:38 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-11 23:39 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 19:39 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-12 11:22 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 02:21 -0700
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-12 21:53 +0200
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 03:37 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 09:49 +0100
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-13 12:58 +0200
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 07:32 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 19:05 +0100
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-14 13:19 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-15 00:01 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-18 14:48 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-26 16:23 -0400
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2015-09-27 00:23 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-26 16:37 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:17 -0400
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:24 -0400
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:46 -0400
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2016-01-16 16:14 +0000
                Re: Smaller C Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-23 13:20 -0500
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2016-01-27 13:52 +0000
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:28 -0400
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2016-01-16 16:31 +0000
                Re: Smaller C Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-23 13:20 -0500
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-18 16:21 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-20 17:25 -0700
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-13 12:43 +0200
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 09:21 +0100
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-13 13:02 +0200
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 19:09 +0100
                Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 13:32 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 18:51 -0400
                Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 18:16 -0700
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 02:36 -0700
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-12 11:56 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 03:45 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 10:28 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 02:53 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 11:17 -0400
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 16:54 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 21:39 -0400
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 20:31 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 09:03 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 19:48 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 21:33 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-14 23:17 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-20 17:37 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-20 23:46 +0100
  Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 21:37 -0700
    Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 22:29 -0700
      Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 03:25 -0700
        Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-12 11:18 -0700
          Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-12 11:39 -0700
          Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 03:47 -0400
            Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 11:31 -0400
          Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 02:00 -0700
            Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 11:31 -0400
            Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-13 09:15 -0700
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 02:45 -0700
      Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-12 10:55 -0700
  Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-15 19:23 -0700
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-16 03:03 -0700
      Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-16 10:17 -0700

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