[9fans] creating a library, simple question

[9fans] creating a library, simple question

[Alberto Cortes]

i am trying to create a library, the source files looks like this:

term% ls
me_util.c
me_util.h
mevents.c
mevents.h
mkfile
term% cat mkfile
< /$objtype/mkfile

LIB=libmevents.a$O

OFILES=\
	mevents.$O\
	me_util.$O\

HFILES=\
	mevents.h\
	me_util.h\

</sys/src/cmd/mklib


"me_util.c" defines some helper functions for my library and...
"me_util.h" declares them.
"mevents.c" defines the functions to be served by the library.
"mevents.h" is the header file to be included by other programs, its only
declares the functions defined in "mevents.c", not the ones in "me_util.c".

How do i prevent other programs that include "mevents.h" and are
linked to my library, from seeing the functions in "me_utils.c"?

Additional explanation:
"me_util.c" declares a "void error(char *s)" function, but other
programs would want to use functions called "error" for sure. How do i
prevent the two "error" functions from collision?

i have seen some libraries with the underscore solution:

void
_error(char *s)

is it a good solution to prevent name collision?





--
http://montoya.aig.uc3m.es/~acortes/index.html

Re: [9fans] creating a library, simple question

[Francisco Ballesteros]

just keep your tools separate in the header and add
a /* internal use only */ comment to that section.
You have examples in some of the libraries, see /sys/src.

If the symbols are extern, nobody can prevent others from using them.

hth

On Fri, 20 Aug 2004 12:15:29 +0200, Alberto Cortes <alcortes@coitt.es> wrote:
> i am trying to create a library, the source files looks like this:
>
> term% ls
> me_util.c
> me_util.h
> mevents.c
> mevents.h
> mkfile
> term% cat mkfile
> < /$objtype/mkfile
>
> LIB=libmevents.a$O
>
> OFILES=\
>         mevents.$O\
>         me_util.$O\
>
> HFILES=\
>         mevents.h\
>         me_util.h\
>
> </sys/src/cmd/mklib
>
> "me_util.c" defines some helper functions for my library and...
> "me_util.h" declares them.
> "mevents.c" defines the functions to be served by the library.
> "mevents.h" is the header file to be included by other programs, its only
> declares the functions defined in "mevents.c", not the ones in "me_util.c".
>
> How do i prevent other programs that include "mevents.h" and are
> linked to my library, from seeing the functions in "me_utils.c"?
>
> Additional explanation:
> "me_util.c" declares a "void error(char *s)" function, but other
> programs would want to use functions called "error" for sure. How do i
> prevent the two "error" functions from collision?
>
> i have seen some libraries with the underscore solution:
>
> void
> _error(char *s)
>
> is it a good solution to prevent name collision?
>
> --
> http://montoya.aig.uc3m.es/~acortes/index.html
>

Re: [9fans] creating a library, simple question

[Charles Forsyth]

with C the usual solution is to give the functions a short prefix
(dbmopen, dbmstore, regcomp, regexec, ndbsearch) or be
in a position to set the standard for everyone else
my clash is your fault.

[9fans] creating a library, simple question

[Alberto Cortes]

On Fri, 20 Aug 2004 17:10:29 +0000, Charles Forsyth wrote:
> with C the usual solution is to give the functions a short prefix
> (dbmopen, dbmstore, regcomp, regexec, ndbsearch) or be
> in a position to set the standard for everyone else
> my clash is your fault.
>
------ end of the original message ------

thanks for the advice, i will use a prefix and also include an
"internal use only" comment on the headers, as nemo suggested.

It is a pity; at first i created a single file with all the functions,
the helper ones declared as "static". But i decided to split it by
virtue of readability :-(


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Re: [9fans] creating a library, simple question

[boyd, rounin]

> thanks for the advice, i will use a prefix and also include an
> "internal use only" comment on the headers, as nemo suggested.

sounds like a bad idea.  use static or restructure.

or limbo ...