Sets the discriminator of the DynUnion to the specified value.
Setting the discriminator to a value that is consistent with the currently active union member
does not affect the currently active member. Setting the discriminator to a value that is inconsistent
with the currently active member deactivates the member and activates the member that is consistent
with the new discriminator value (if there is a member for that value) by initializing the member
to its default value.
Setting the discriminator of a union sets the current position to 0 if the discriminator value
indicates a non-existent union member (has_no_active_member returns true in this case).
Otherwise, if the discriminator value indicates a named union member, the current position is set to 1
(has_no_active_member returns false and component_count returns 2 in this case).
TypeMismatch - if the TypeCode of the parameter is not equivalent to the TypeCode
of the union's discriminator
Sets the discriminator to a value that does not correspond to any of the unions case labels.
It sets the current position to zero and causes component_count to return 1.
TypeMismatch - if the union has an explicit default case or if it uses the entire range
of discriminator values for explicit case labels
Returns true if the union has no active member, that is, the unions value consists solely
of its discriminator because the discriminator has a value that is not listed as an explicit case label.
Calling this operation on a union that has a default case returns false.
Calling this operation on a union that uses the entire range of discriminator values
for explicit case labels returns false.
Returns the currently active member. Note that the returned reference remains valid only
for as long as the currently active member does not change. Using the returned reference
beyond the life time of the currently active member raises OBJECT_NOT_EXIST.