operator
shelf-name lastmost
lastmost
can be used to identify a shelf item to be accessed, wherever an item indexer, [...]
or key {...}
can be used. The lastmost
indexer always accesses the last item on the shelf.
Note that the syntax:
shelf-name lastmost
and
shelf-name [number of shelf-name]
are identical when used to access an item on a shelf. They behave differently when they are used to set the currently selected item:
using
prefix
In the two cases above, when the default item of the shelf or function argument is accessed, the lastmost
item is recalculated, while number of
is not. This means that when the default item is set to lastmost
, it will always be the last item on the shelf, regardless of how the shelf changes.
When the default item on a shelf is set to lastmost
, it will always be the last item on the shelf regardless of how the shelf changes. When used to set the currently selected item, lastmost
behaves differently than number of
.
In this example, which uses lastmost
,
process local integer c variable clear c set new c to 1 using c lastmost do output "The value is %d(c)%n" set new c to 2 output "The value is %d(c)%n" set new c to 3 output "The value is %d(c)%n" done
the output is:
The value is 1 The value is 2 The value is 3
However, when the default is set to the last item with "[number of c]
":
process local integer c variable clear c set new c to 1 using c [number of c] do output "The value is %d(c)%n" set new c to 2 output "The value is %d(c)%n" set new c to 3 output "The value is %d(c)%n" done
the output is:
The value is 1 The value is 1 The value is 1
This is because the number of items on shelf c is just 1. That becomes the numeric index of the shelf for the duration of using
.
Note that it cannot be assumed that the "lastmost" item of a passed shelf is its current item. The following function takes this possibility into account, and the using
keyword is used to ensure that references to the stream code-set
refer only to the newly created item.
define function add-new-codes (modifiable stream code-set, value string new-codes) as using code-set lastmost do new code-set open code-set as buffer repeat scan new-codes match letter => one-code put code-set "%ux(one-code)" match any ; skip again close code-set done