Strong Using - Red Hat ENTERPRISE LINUX 4 Manual

262
specifying a relative
and 65535 inclusive. Lower numbers indicate a higher priority.
In the following example,
tribute has reversed that order:
Some_Class
Some_Class
Note that the particular values of
java_interface
This type attribute informs C++ that the class is a Java interface. It may only be applied to classes
declared within an
dispatched using GCJ's interface table mechanism, instead of regular virtual table dispatch.
See also Section 7.9 Strong Using.

7.9. Strong Using

Caution: The semantics of this extension are not fully defined. Users should refrain from using this ex-
tension as its semantics may change subtly over time. It is possible that this extension wil be removed
in future versions of G++.
A using-directive with
ways:
Templates from the used namespace can be specialized as though they were members of the using
•
namespace.
The using namespace is considered an associated namespace of all templates in the used namespace
•
for purposes of argument-dependent name lookup.
This is useful for composing a namespace transparently from implementation namespaces. For exam-
ple:
namespace std {
namespace debug {
template class T
}
using namespace debug __attribute ((__strong__));
template struct A int
template class T
}
int main()
{
f (std::A float ());
f (std::A int ());
}
, a constant integral expression currently bounded between 101
priority
would normally be created before
A
A __attribute__ ((init_priority (2000)));
B __attribute__ ((init_priority (543)));
priority
extern "Java"
__attribute ((strong))
struct A { };
{ };
void f (A T );
Chapter 7. Extensions to the C++ Language
do not matter; only their relative ordering.
block. Calls to methods declared in this interface will be
is stronger than a normal using-directive in two
// ok to specialize
// lookup finds std::f
, but the
B init_priority
at-