Re: Exhaustive list of unusable names
"Gene Bushuyev" wrote:
"Frederick Gotham" <fgothamNO@SPAM.com> wrote in message
news:Xns97E8BFFB8B436fgothamNOSPAM@194.125.133.14...
[...]
I have another example, reproduced below. If memory serves
me right, I did at one time have a compiler which wouldn't
compile it. Do you think it should compile? It's based on
creating our own function called "strlen".
#include <cstddef>
#include <cstring>
std::size_t strlen( const char* p )
{
std::size_t len = -1; /* Max value */
while ( ++len, *p++ );
return len;
}
It should compile, the two functions are in different
namespaces.
That's the theory. In most implementations, they aren't, and I
think that C++0x will no longer require that they be.
I think it should compile. Linking it with an application isn't
guaranteed to work, however. And if the link succeeds, the
program might not have the behavior you want.
Just need to remember that ADL may create unexpected
customization points when parameters are UDTs. Also if your
functions are exposed in the libraries it may create problems
for some users that have a nasty habit of opening all
namespaces with "using directive."
It's trickier than that here. <cstring> very likely contains
something like:
extern "C" std::size_t strlen( const char* p ) ;
In which case, if the implementation has actually declared
strlen in the global namespace (usually the case), his
definition is the definition of the "C" function. (See ?7.5/6.)
Given the way most linkers work, his definition will be used
instead of the one in the standard library.
Now modify the code to return len - 1, and watch the fun
begin:-).
We're in trouble with the above code if the STL version of
strlen is a macro.
Standard library is not allowed to redefine standard C
functions as macros.
No, but they are allowed to declare them 'extern "C"'. And
while formally not yet allowed, they usually also declare them
in the global namespace.
As a matter of principle, I would avoid any global function with
a name starting with either str or is, followed by a small
letter.
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James Kanze GABI Software
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