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Sample Programs from NeXSTEP 3.3

/*
MultiBinder.h
A Binder that knows about multiple result sets 

MultiBinders are used instead of DBBinders in order to retrieve
non-rectangular return results from Sybase or other similar stored
procedures.

MultiBinders only work in the mode where the binder itself creates
the recordPrototype for the binder.  You cannot provide your own
recordPrototypes for the MultiBinder.

If you know exactly the sequence of properties the stored procedure
will be returning to you, then:
1.  Create a List for each [rectangular] result set the stored
    procedure returns.  Each List should contain, in the order the
    stored procedure will return them, the attributes returned from
    the database model.  Note that the attributes need not, in
    the case of the MultiBinder, be from the same entity.
2.  Place all these Lists, in the order in which those result
    sets will be returned by the stored procedure, into a temporary
    List.  Pass that temporary list as the argument to
    [multiBinder initFromPropertyLists:].  After initializing the binder,
    the temporary list may be freed.  The underlying lists created in
    step #1 are now owned by the MultiBinder, and will be freed
    when the MultiBinder is freed.
3.  Invoke the stored procedure via [multiBinder evaluateString:].
4.  Repeatedley call [multiBinder setNext].  You can then call 
    [multiBinder valueForProperty:] for each property.  Use the 
    delegate method binderDidChangeResultSet: to find out when you
    cross result set boundaries.
5.  All result sets have been retrieved when [multiBinder setNext]
    returns nil.  Note that you should have received as many calls
    to binderDidChangeResultSet: as there were result sets returned
    from your stored procedure.

If you want to simply receive whatever the stored procedure happens
to return, either because of your programs' task or because the 
stored procedure conditionally returns different things:
1.  Pass nil as the argument to [MultiBinder initFromPropertyLists:].
2.  Repeatedley call [multiBinder setNext].  You should interrogate
    the binder via [multiBinder getCurrentProperies:] to get the
    new list of properties whenever the delegate method
    binderDidChangeResultSet: is called.  DO NOT call getProperties:.
3.  All rows of all result sets are retrieved when 
    [multiBinder setNext] returns nil.

*/

#import <dbkit/dbkit.h>

@interface MultiBinder:DBBinder
{
    unsigned int	currentResultSet; /*  index into the list of lists */
    List		*propListList; /* a list of property lists for the result sets */
}

- initFromPropertyLists:(List *)propLists; /*  copies subsidiary lists out of propLists */
- (unsigned int)currentResultSet; /* returns the index of the current result set */
- (List *)getCurrentProperties:(List *)aList; /* fills aList with the current properties */

@end

@interface Object (MultiBinderDelegateMethods)
- binderWillChangeResultSet:binder; /* called before changing result sets */
- binderDidChangeResultSet:binder; /* called before fetching from a new result set */
@end

@interface DBBinder (MultiBinderMethods)
- (List *)getCurrentProperties:(List *)aList;
@end

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