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| Newsgroups | comp.lang.c |
|---|---|
| Subject | Re: global/static variables & loops |
| References | (6 earlier) <jhgt9t$hkn$1@dont-email.me> <878vk3ao7m.fsf@huddi.jernurt.dk> <jhh2sd$kt1$1@dont-email.me> <87y5s396wj.fsf@huddi.jernurt.dk> <jhh6d5$aps$1@dont-email.me> |
| From | Anders Wegge Keller <wegge@wegge.dk> |
| Date | 2012-02-15 23:10 +0100 |
| Message-ID | <87ty2r929y.fsf@huddi.jernurt.dk> (permalink) |
| Organization | SunSITE.dk - Supporting Open source |
James Kuyper <jameskuyper@verizon.net> writes:
> On 02/15/2012 03:30 PM, Anders Wegge Keller wrote:
> That's just a global dressed up in fancy clothes. It has all of the
> disadvantages of a global, while being unnecessarily more complicated
> than defining a global.
I'm happy to see that I managed to make myself clear. But sadly, I've
seen text books and style guides that advocates exactly this pattern.
...
>> I'm not trying to justify "All data should be global", as you seem to
>> imply. I'm questioning "No data should be global". There is a world
>> between those two statements.
> I'd argue for "little, if any, data should be global". The only
> objects that should have external linkage are those which will be
> used almost everywhere in a program, and in my experience there
> aren't many of those.
Apart from our embedded code, most of what I write for a living are
event-driven processes, that do a lot of IPC with each other. That
gives quite a lot of state, that either has to be a global, or be
dressed up as something else with the same properties, as the naive
example from last post.
> If there are, poor design is usually to blame. To take your example,
> I could quite easily imagine wanting to have different debug levels
> in different parts of the program, which would make a single global
> debug level inappropriate.
Actually you have CHAR_BIT * (sizeof(int)/sizeof(char)) debug
masks. If that isn't enough, the process should probably be split into
two or more parts that are a bit more focused.
>> Try implementing GNU ls without globals. I know that the whole lot
>> are statics, since the code is in just one TU, but imagine something
>> of a similar magnitude then. The first few levels of functions will
>> have prototypes of several pages.
> I don't have time to implement the entirety of ls; if the sheer
> complexity of ls is your point, then I won't be able to address it
> directly.
I stated ls as an antithesis to
"Variables which are local to main() and are passed by a pointer
to subroutines need not be passed to all subroutines, but only
the ones that actually need to have access to those variables, and
that could be a different set of subroutines for different
variables."
Dividing the whole set of options into structs that are passed on a
stict "need to access"-basis for each individual function called from
main() will in effect lead to passing almost any command line option
as a separate argument down the call graph from main().
--
/Wegge
Leder efter redundant peering af dk.*,linux.debian.*
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global/static variables & loops Rob Janecek <robs@invalid.com> - 2012-02-14 19:56 +0000
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-14 12:42 -0800
Re: global/static variables & loops Stephen Sprunk <stephen@sprunk.org> - 2012-02-14 15:01 -0600
Re: global/static variables & loops Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-14 20:35 -0500
Re: global/static variables & loops Philip Lantz <prl@canterey.us> - 2012-02-14 21:18 -0800
Re: global/static variables & loops pete <pfiland@mindspring.com> - 2012-02-15 00:53 -0500
Re: global/static variables & loops Jonathan Leffler <jleffler@earthlink.net> - 2012-02-18 21:15 -0800
Re: global/static variables & loops Kaz Kylheku <kaz@kylheku.com> - 2012-02-19 06:05 +0000
Re: global/static variables & loops Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-22 03:15 +0200
Re: global/static variables & loops Shao Miller <sha0.miller@gmail.com> - 2012-02-19 04:14 -0500
Re: global/static variables & loops Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-02-19 12:32 +0000
Re: Array 'typedef's and exclusive use of '->' versus '.' Shao Miller <sha0.miller@gmail.com> - 2012-02-19 17:00 -0500
Re: Array 'typedef's and exclusive use of '->' versus '.' Keith Thompson <kst-u@mib.org> - 2012-02-19 16:43 -0800
Re: Array 'typedef's and exclusive use of '->' versus '.' Shao Miller <sha0.miller@gmail.com> - 2012-02-19 20:32 -0500
Re: Array 'typedef's and exclusive use of '->' versus '.' Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-22 03:27 +0200
Re: Array 'typedef's and exclusive use of '->' versus '.' Shao Miller <sha0.miller@gmail.com> - 2012-02-25 02:19 -0500
Re: Array 'typedef's and exclusive use of '->' versus '.' Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-25 10:14 +0200
Re: global/static variables & loops "BartC" <bc@freeuk.com> - 2012-02-15 10:47 +0000
Re: global/static variables & loops Kaz Kylheku <kaz@kylheku.com> - 2012-02-15 11:42 +0000
Re: global/static variables & loops "BartC" <bc@freeuk.com> - 2012-02-15 12:54 +0000
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-15 05:17 -0800
Re: global/static variables & loops Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-22 03:28 +0200
Re: global/static variables & loops August Karlstrom <fusionfile@gmail.com> - 2012-02-15 15:19 +0100
Re: global/static variables & loops Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-22 03:12 +0200
Re: global/static variables & loops Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-15 01:23 -0800
Re: global/static variables & loops August Karlstrom <fusionfile@gmail.com> - 2012-02-15 14:03 +0100
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-15 05:20 -0800
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 08:41 -0500
Re: global/static variables & loops Kaz Kylheku <kaz@kylheku.com> - 2012-02-16 00:20 +0000
Re: global/static variables & loops Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-15 21:02 -0500
Re: global/static variables & loops "BartC" <bc@freeuk.com> - 2012-02-16 10:03 +0000
Re: global/static variables & loops Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-16 07:58 -0500
Re: global/static variables & loops Markus Wichmann <nullplan@gmx.net> - 2012-02-19 20:44 +0100
Re: global/static variables & loops Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-19 15:37 -0500
Re: global/static variables & loops Kaz Kylheku <kaz@kylheku.com> - 2012-02-22 05:01 +0000
Re: global/static variables & loops Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-22 08:12 -0500
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 15:55 +0100
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 11:05 -0500
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-15 09:13 -0800
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 18:25 +0100
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 13:25 -0500
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-15 10:51 -0800
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 14:45 -0500
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 20:47 +0100
Re: global/static variables & loops Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-16 04:45 -0800
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-16 14:25 +0100
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-16 08:10 -0800
Re: global/static variables & loops Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-17 00:59 -0800
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 20:30 +0100
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 15:00 -0500
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 21:30 +0100
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 16:00 -0500
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 23:10 +0100
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-15 15:50 -0800
Re: global/static variables & loops James Kuyper <jameskuyper@verizon.net> - 2012-02-15 19:50 -0500
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-16 14:36 +0100
Re: global/static variables & loops Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-16 03:29 -0800
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-15 23:37 +0100
Re: global/static variables & loops Kaz Kylheku <kaz@kylheku.com> - 2012-02-16 00:23 +0000
Re: global/static variables & loops Anders Wegge Keller <wegge@wegge.dk> - 2012-02-16 01:29 +0100
Re: global/static variables & loops Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-02-15 21:20 -0500
Re: global/static variables & loops Shao Miller <sha0.miller@gmail.com> - 2012-02-15 22:24 -0500
Re: global/static variables & loops Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-16 01:08 -0800
Re: global/static variables & loops Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-02-16 03:17 -0800
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