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kanze@gabi-soft.fr
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 Posted: Fri Oct 29, 2004 5:21 pm Post subject: linkage of atexit |
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In §18.3, the standard specifies two possible signatures for atexit. Is
it the intent that an implementation must provide both?
- If yes, why isn't this specified explicitly, as it is, for example,
in the functions in §21.4?
- If no, then presumably the implementation is required to provide one
or the other -- this is simply an explicit example of §17.4.2.2/2.
In this case, however, how can one possibly use the function in
portable code, since the parameter types of the two functions are
different?
--
James Kanze GABI Software http://www.gabi-soft.fr
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Alberto Barbati
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| Posted: Sun Oct 31, 2004 8:11 am Post subject: Re: linkage of atexit |
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[email]kanze (AT) gabi-soft (DOT) fr[/email] wrote:
| Quote: | In §18.3, the standard specifies two possible signatures for atexit. Is
it the intent that an implementation must provide both?
- If yes, why isn't this specified explicitly, as it is, for example,
in the functions in §21.4?
- If no, then presumably the implementation is required to provide one
or the other -- this is simply an explicit example of §17.4.2.2/2.
In this case, however, how can one possibly use the function in
portable code, since the parameter types of the two functions are
different?
|
The functions in §21.4 are a bit different from atexit, because they
don't involve linkage specifications. More relevant examples are
functions bsearch and qsort in §25.4 where in fact the signatures with
both "C" and "C++" linkage are explicitly specified. I guess the
difference is due to the fact that the interpretation of
pointer-to-function arguments are affected by the linkage specification,
so I believe atexit should also provide both signature and §18.3 should
specify that explicitly.
That makes me think, however. Instead of requiring two signatures like:
extern "C" int atexit(void (*f)(void))
extern "C++" int atexit(void (*f)(void))
an alternative set if signatures could have been:
extern "C" typedef void (*atexit_handler_c)();
extern "C++" typedef void (*atexit_handler_cpp)();
int atexit(atexit_handler_c);
int atexit(atexit_handler_cpp);
I guess the former choice has been followed for better compatibility
with the C library, but the latter choice would have been more
consistent with the approach followed in §21.4.
Just my €0.02
Alberto
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James Kuyper
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| Posted: Mon Nov 01, 2004 7:30 am Post subject: Re: linkage of atexit |
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[email]AlbertoBarbati (AT) libero (DOT) it[/email] (Alberto Barbati) wrote in message news:<YSJgd.8310$Es2.168971 (AT) twister2 (DOT) libero.it>...
| Quote: | In §18.3, the standard specifies two possible signatures for atexit. Is
it the intent that an implementation must provide both?
|
I believe it is; the intent being to allow registration of functions
with either "C" or "C++" language linkage.
| Quote: | - If yes, why isn't this specified explicitly, as it is, for example,
in the functions in §21.4?
|
Good question.
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