
shelf_inc_and_get(+ShelfHandle, +Index, -NewValue)

   Increment an integer slot within a shelf object and get the new value

Arguments
   ShelfHandle         A shelf handle or shelf name
   Index               An integer
   NewValue            A variable or integer

Type
   Non-logical Variables, Arrays, Bags, Shelves and Stores

Description
	This looks up the entry in the Index'th slot of the shelf object
	denoted by ShelfHandle, and if such an entry exists, and is of integer
	type, it is incremented by one.  The new value is returned as NewValue.
	This predicate is a shorthand for:

	shelf_inc_and_get(ShelfHandle, Index, C1) :-
	    with_mutex(ShelfHandle, (
		shelf_get(ShelfHandle, Index, C0),
		C1 is C0 + 1,
		shelf_set(ShelfHandle, Index, C1))
	    ).

	The slots are numbered from 1 to the maximum which was determined
	during shelf creation (but note that ECLiPSe's struct-syntax can
	be used to give the slots symbolic names, see struct/1).

	Note: If ShelfHandle is not a handle, then it must be an atom or a
	compound term, and the shelf is identified by this term's toplevel
	functor together with the context module.
    

Modes and Determinism
   shelf_inc_and_get(+, +, -) is det

Exceptions
     4 --- ShelfHandle is not instantiated
     5 --- Index is not instantiated
     5 --- ShelfHandle is not a shelf
     5 --- Index is not an integer
     6 --- Index is less than 1 or greater than the number of slots on the shelf
     6 --- The counter value exceeds an implementation-defined limit (at least 2^31)
    40 --- ShelfHandle refers to an already destroyed shelf

Examples
   
    	?- shelf_create(s(5),S), shelf_inc_and_get(S,1,New).

	S = $&(shelf,"36nzz7")
	New = 6
	Yes (0.00s cpu)
    

See Also
   shelf_create / 2, shelf_create / 3, shelf_inc / 2, shelf_set / 3, shelf_get_and_dec / 3, struct / 1
