Each type declaration in the schema module is translated into one
C++ type declaration with the same name. In addition, for each type
<T> there is a C++ constant <T>_type which denotes the
corresponding (persistent) object of the base type that the schema compiler has
generated. It can be used to check the actual type of an object. This way
of dynamic type evaluation allows a case distinction by the type of an
object.
Note that for a type declared by
typedef A B;the constant
B_type denotes the base type object for A, that
means A_type == B_type.
Example:
The following C++ code checks, whether an object o that is statically
declared of type sos_Object actually is of type sos_String;
if so, it is explicitly converted to this type, and the method
make_Cstring
of this type is called. The conversion is necessary, since the method
is no method of class sos_Object, so o.make_Cstring() would
produce a C++ compile time error.
sos_Object o;
...
if (o.has_type (sos_String_type))
{ sos_String s = sos_String::make (o);
sos_Cstring cs = s.make_Cstring();
cout << cs;
delete cs;
}