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iXML Library - Down Casts

For reference variables with the static type of the interfaces IF_IXML_... in iXML Library, the usual down casts with the casting operators ?= and CAST can be used for assignments from more general to more specific types. If a down cast fails, the exception CX_SY_MOVE_CAST_ERROR is raised, which can be handled in a TRY control structure (as usual).

The method QUERY_INTERFACE of the interface IF_IXML_UNKNOWN (implemented by every object in iXML Library) can be used to make handling of exceptions simpler:

special_reference ?= general_reference->query_interface( type ).

type can be used to specify the required special type by specifying a constant ixml_iid... from the type group IXML. A successful down cast runs as if no method is called. If an error occurs, the exception is handled in the method and an initial reference returned.

Example

See iXML Library, Down Casts