Re: Including multiple files with same name?
On 09.05.2010 15:44, * none:
I have the following structure in a src folder:
A/X
A/X/x.h
A/X/x.cpp
B/X
B/X/x.h
B/X/x.cpp
where A/X/x.h is:
#ifndef A_X_H
#define A_X_H
namespace A {
class X {
};
}
#endif
And:
where B/X/x.h is:
#ifndef B_X_H
#define B_X_H
namespace B {
class X {
};
}
#endif
But how do I include multiple files with the same name?
The language standard is silent on the issue of how an #include path specifies a
header file. But in practice all compilers (including Windows compilers) accept
the *nix convention of writing
#include "A/X/x.h"
or
#include <A/X/x.h>
The standard does however specify the general difference between "..." and
<...>. Namely that the former may look in some additional places first. And if
that fails, the search continues as with the latter form.
In practice, at least when you only specify a filename, with current compilers
the additional search for the "..." form includes to look in the directory of
the file where the #include directive appears.
I guess this should be possible since that is the whole point with
namespaces (to have multiple types with the same name but located in
different namespaces).
In C++ namespaces have no other relation to directories than what you establish
yourself. In general it's not a good idea to couple these concepts too tightly.
Too tight coupling between logical packaging (namespaces) and physical packaging
(directories) can lead to "namespace hell", as well as "directory hell" --
borrowing some Microsoft terminology (they invented "DLL hell").
Cheers & hth.,
- Alf
(blog at <url: http://alfps.wordpress.com/>)