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Groups > comp.lang.c > #381993
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: What I've learned in comp.lang.c |
| Date | 2024-02-07 16:13 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <87a5octfqd.fsf@bsb.me.uk> (permalink) |
| References | (6 earlier) <upuf0v$13gvv$1@dont-email.me> <upvcv5$1bcum$1@dont-email.me> <upvgp1$1bs8q$1@dont-email.me> <87y1bwtuss.fsf@bsb.me.uk> <upvtvi$1e5or$1@dont-email.me> |
Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
> On 07/02/2024 10:47, Ben Bacarisse wrote:
>> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
>>
>>> On 07/02/2024 07:54, David Brown wrote:
>>>> On 07/02/2024 00:23, Lawrence D'Oliveiro wrote:
>>>>> On Tue, 6 Feb 2024 09:44:20 +0100, David Brown wrote:
>>>>>
>>>>>> They reuse "temp" variables instead of making new ones.
>>>>>
>>>>> I like to limit the scope of my temporary variables. In C, this is as
>>>>> easy
>>>>> as sticking a pair of braces around a few statements.
>>>> Generally, you want to have the minimum practical scope for your local
>>>> variables. It's rare that you need to add braces just to make a scope
>>>> for a variable - usually you have enough braces in loops or conditionals
>>>> - but it happens.
>>>>
>>> The two common patterns are to give each variable the minimum scope, or to
>>> decare all variables at the start of the function and give them all
>>> function scope.
>> The term "function scope" has a specific meaning in C. Only labels have
>> function scope. I know you are not very interested in using exact
>> terms, but some people might like to know the details.
>>
> To explain this, if we have
What is the "this" that you are explaining?
> void function(void)
> {
> int i;
>
> for (i = 0; i < 10;; i++)
> dosomething();
> if ( condition)
> {
> int i;
>
> for (i = 0; i < 11; i++)
> dosomething();
> if (i == 10)
> /* always false */
> }
> }
>
> The first i is not in scope when we test for i == 10 and the test will be
> false. So "fucntion scope" isn't the term.
"function scope" is not the term because only labels have function
scope. This example does not explain anything about the term
"functions scope" -- even why it's the wrong term.
> However if we have this:
>
> void fucntion(void)
> {
> label:
> dosomething();
> if (condition)
> {
> label:
> dosomething();
> }
> got label:
(you mean "goto label;")
> }
>
> Then it is a error. Both labels are in scope and that isn't allowed.
The key thing about the scope of labels is that they can be used before
that are defined:
int *f(int *p)
{
if (!p) goto error:
...
error:
return p;
}
>> Since you want to argue for the peculiar (but common) practice of giving
>> names the largest possible scope (without altering their linkage) you
>> need a term for the outer-most block scope, but "function scope" is
>> taken.
>>
> So "function scope" isn't the correct term. So we need another. I expect
> that at this point someone will jump in and say it must be "Malcolm
> scope". As you say, it's common enough to need a term for it.
I see no reason not to call it "the outer-most block scope".
>>> The case for minimum scope is the same as the case for scope itself.
>> Someone might well misinterpret the term "minimum scope" since it would
>> require adding lots of otherwise redundant braces. I *think* you mean
>> declaring names at the point of first use. The resulting scope is not
>> minimum because it often extends beyond the point of last use.
>
> Yes, I don't mean literally the minimum scope that would be possible by
> artificially ending a block when a variable is used for the last time. No
> one would do that. I mean that the variable is either declared at point of
> first use or, if this isn't allowed because of the C version, at the top of
> the block in which it is used. But also that variables are not reused if in
> fact the value is discarded between statements or especially between
> blocks.
>
>> Other people, not familiar with" modern" C, might interpret the term to
>> mean declaring names at the top of the inner-most appropriate block.
>>
> Top of the block or point of first use?
I don't know what you are asking. I was trying to point out these two
possible meanings for "minimum scope".
>>> The
>>> variable is accessible where it is used and not elsewhere, which makes it
>>> less likely it will be used in error, and means there are fewer names to
>>> understand.
>> The case for declaration at first use is much stronger than this. It
>> almost always allows for a meaningful initialisation at the same point,
>> so the initialisation does not need to be hunted down a checked. For
>> me, this is a big win. (Yes, some people then insist on a dummy
>> initialisation when the proper one isn't know, but that's a fudge that
>> is, to my mind, even worse.)
>>
> If you go for top of block and you don't have a value, you either
> intialise, usually to zero, or leave it wild. Neither is ideal. But it
> rarely makes a big difference. However if you go for policy two, all the
> variables are either given initial values at the top of the function or
> they are not given initial values at the top of the function,and so you can
> easily check, and ensure that all the initial values are consistent woth
> each other.
What?
>> We could call it outer-most block scope rather than re-use a term with
>> an existing, but different, technical meaning.
>>
> The variable has scope within the function, within the whole of the
> function, and the motive is that the function is the natural unit of
> thought. So I think we need the word "function".
You need the word function. I don't.
--
Ben.
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What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-05 01:09 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-05 05:58 +0000
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-04 22:49 -0800
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-05 07:03 +0000
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-04 23:51 -0800
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-04 23:52 -0800
Re: What I've learned in comp.lang.c Jan van den Broek <balglaas@dds.nl> - 2024-02-05 08:36 +0000
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-05 18:23 +0200
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-05 18:32 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-05 20:53 +0100
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-05 20:53 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-06 09:44 +0100
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-06 01:03 -0800
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-06 13:41 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-06 13:08 +0100
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-06 23:23 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 08:54 +0100
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-07 08:59 +0000
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-07 10:47 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 11:04 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 14:21 +0100
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 14:24 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 21:30 +0100
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-07 15:36 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 18:05 +0000
Re: What I've learned in comp.lang.c scott@slp53.sl.home (Scott Lurndal) - 2024-02-07 18:26 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 19:53 +0000
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-07 21:38 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 00:29 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 21:37 +0100
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 22:52 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-08 01:13 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-08 02:09 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-08 03:07 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-08 14:17 +0000
Re: What I've learned in comp.lang.c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-02-08 16:02 -0800
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-09 00:48 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-09 08:53 +0100
Re: What I've learned in comp.lang.c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-02-10 21:55 -0800
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-08 13:01 +0100
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-08 11:37 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 12:10 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-08 13:24 +0100
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 13:03 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-08 13:17 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-08 16:52 +0100
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-08 17:17 +0000
Re: What I've learned in comp.lang.c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-02-09 14:50 -0800
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-07 12:44 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 14:49 +0100
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-07 16:13 +0000
Re: What I've learned in comp.lang.c Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-02-07 08:21 -0800
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 14:01 +0100
Re: What I've learned in comp.lang.c Richard Harnden <richard.nospam@gmail.invalid> - 2024-02-07 13:21 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-07 13:42 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 16:17 +0100
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-07 21:34 +0000
Re: What I've learned in comp.lang.c scott@slp53.sl.home (Scott Lurndal) - 2024-02-07 16:21 +0000
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-08 13:26 +0200
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-07 10:04 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 14:51 +0100
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-07 15:30 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-07 15:45 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 21:44 +0100
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 00:33 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-08 01:30 +0000
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-08 01:38 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 02:21 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-08 03:07 +0000
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-08 11:45 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 12:15 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-08 13:29 +0100
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-08 12:55 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-09 09:02 +0100
Re: What I've learned in comp.lang.c scott@slp53.sl.home (Scott Lurndal) - 2024-02-08 16:09 +0000
Re: What I've learned in comp.lang.c Richard Harnden <richard.nospam@gmail.invalid> - 2024-02-08 16:28 +0000
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-08 17:13 +0000
Re: What I've learned in comp.lang.c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-02-08 17:53 -0800
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-05 19:02 +0200
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-05 23:28 +0000
Re: What I've learned in comp.lang.c Richard Harnden <richard.nospam@gmail.invalid> - 2024-02-05 23:40 +0000
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-06 01:46 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-06 09:54 +0100
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-05 16:03 -0800
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-05 16:06 -0800
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-06 09:50 +0100
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-06 01:01 -0800
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-06 23:24 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 08:56 +0100
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-07 12:09 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 15:03 +0100
Re: What I've learned in comp.lang.c scott@slp53.sl.home (Scott Lurndal) - 2024-02-07 16:25 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 21:49 +0100
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-07 13:04 -0800
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-07 23:37 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-08 08:52 +0100
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-09 15:55 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-09 15:29 +0100
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-09 16:52 +0200
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-09 17:22 +0100
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-10 07:18 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-10 17:11 +0100
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-10 21:23 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-11 14:01 +0100
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-07 21:41 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 02:18 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-07 09:30 +0100
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-07 09:04 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-07 23:24 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-08 01:46 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-08 02:50 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-08 11:08 +0000
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-08 13:10 +0200
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-08 17:48 +0000
Re: What I've learned in comp.lang.c Michael S <already5chosen@yahoo.com> - 2024-02-08 21:30 +0200
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-08 20:39 +0000
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-08 13:39 -0800
Re: What I've learned in comp.lang.c Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-02-08 14:18 -0800
Re: What I've learned in comp.lang.c gazelle@shell.xmission.com (Kenny McCormack) - 2024-02-08 22:29 +0000
Re: What I've learned in comp.lang.c "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-08 14:43 -0800
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-09 09:12 +0100
Re: What I've learned in comp.lang.c Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-02-04 23:36 -0800
Re: What I've learned in comp.lang.c scott@slp53.sl.home (Scott Lurndal) - 2024-02-05 14:52 +0000
Re: What I've learned in comp.lang.c gazelle@shell.xmission.com (Kenny McCormack) - 2024-02-05 22:58 +0000
Re: What I've learned in comp.lang.c Jim Jackson <jj@franjam.org.uk> - 2024-02-05 18:01 +0000
Re: What I've learned in comp.lang.c Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-02-05 08:29 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 01:35 +0000
Re: What I've learned in comp.lang.c Kaz Kylheku <433-929-6894@kylheku.com> - 2024-02-07 02:26 +0000
Re: What I've learned in comp.lang.c bart <bc@freeuk.com> - 2024-02-07 10:47 +0000
Re: What I've learned in comp.lang.c Dan Purgert <dan@djph.net> - 2024-02-05 11:03 +0000
Re: What I've learned in comp.lang.c David Brown <david.brown@hesbynett.no> - 2024-02-05 13:15 +0100
Re: What I've learned in comp.lang.c Ben Bacarisse <ben.usenet@bsb.me.uk> - 2024-02-05 14:09 +0000
Re: What I've learned in comp.lang.c Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-02-05 23:29 +0000
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