This is a simple expansion expanding to the name of the interface and is
not qualified like $javainterfacename and $csinterfacename.
Expansion within typemaps is much like $javainterfacename otherwise.
Note that expansion within the pure java code typemap,
'javainterfacecode' and similarly pure C# code typemap,
'csinterfacecode' works like $javaclassname/$csclassname and
$&interfacename should not be used, just $interfacename.
Support expansion of name attribute in: %feature("interface", name="%s")
%s expands to the proxy class name and all the usual %rename functions
can be used (regex, strip, camelcase etc) to derive the interface name
from the proxy class name.
Rename $interfacename family of special variables to $javainterfacename for Java
Rename $interfacename family of special variables to $csinterfacename for C#
This is to free up $interfacename for simple interface name expansion in forthcoming commit
pgcpp was turned off but it is still needed for the interface feature
to prevent premature garbage collection of the proxy class being passed
into the C++ layer.
The C++ type must be last in the argument list to support templates with
multiple arguments which are separated by commas.
Affects DECLARE_INTERFACE and DECLARE_INTERFACE_RENAME.
