[xsd-users] type inheritance/substitution and generated class interface

[Boris Kolpackov]

Hi Sumant,

Sumant Tambe <sutambe at dre.vanderbilt.edu> writes:

> 1. Once the XML is parsed and and in-memory object model is created, how  
> do I downcast from base to derived type? Specifically from the example,  
> how do I know that a Person is in fact a Superman and get a Superman  
> type of object from the Person object. I tried dynamic_cast thinking  
> that person object reference might be polymorphic, but it does not seem  
> to work.

The two most common reasons why this does not work are:

1. You haven't compiled your schemas with the --generate-polymorphic
   option.

2. You have made a "sliced" copy of the object model node. When dealing
   with polymorphic object models you should use references or make
   complete copies using the _clone() function.

For more information see Section 2.11, "Mapping for xsi:type and Substitution
Groups" in the C++/Tree Mapping User Manual:

http://www.codesynthesis.com/projects/xsd/documentation/cxx/tree/manual/#2.11

As well as the polymorphism example in th examples/cxx/tree/ directory.


> 2. Does substitutionGroup have any effect on the generated class  
> interface?

No, substitution groups are handled automatically by the generated 
code. Unless you use DOM, there is way to tell whether xsi:type or
the substitution groups mechanism was used to provide the dynamic 
type.

Boris