did anyone here, by chance, implemented common data strucutres like stacks and queues, like stacks with first in last out behaviour and first in first out behaviour...
Hi Andre,
I have used LIFO queues in HyperTalk and Transcript.
The queues are simply global or declared local variables containing lists of transaction requests. Various handlers check the last line of the queue and do different things depending on transaction type.
Example: OenoLog has a Wine Lot screen where one can add, edit, & delete wine lots. The screen includes a "Thumbs Up" button the user clicks to complete a transaction. When the user initiates a transaction, "Add", "Edit", or "Delete" is append to the queue in a new trailing line. On mouseUp the "Thumbs Up" handler checks the last line of the queue to determine how to process the data in the window.
It can get more complicated: Suppose I'm in the middle of a Wine Lot Edit transaction, and when I'm shown the Grape Variety screen to select the correct variety, it isn't listed. I can interrupt the Wine Lot Edit transaction and initiate a Grape Variety Add transaction. The queue now lists "Edit" on one line and "Add" on the following line. The "Thumbs Up" button on the Grape Variety screen will process the Add and delete the last line of the queue before returning the new Grape Variety to the Wine Lot screen and continuing the Edit.
And it can get even more complicated: Suppose I'm processing a Winemaking transaction, and when I get to the source tank selection stage I find the tank hasn't been identified to the system. I must interrupt the Winemaking Add transaction and initiated a Tank Add transaction. The Tank Add transaction must be interrupted by a Wine Lot Add transaction if the Wine Lot in the tank has not been identified to the system. In turn, that transaction can be interrupted to initiate Grape Variety Add and Vineyard Add transactions is those items are missing.
The use of queue-supported, interruptible transactions allows, among other things, the user to immediately begin transaction processing with NO initial setup, if desired.
Anything more you'ld like to know. --
Rob Cozens CCW, Serendipity Software Company
"And I, which was two fooles, do so grow three; Who are a little wise, the best fooles bee."
from "The Triple Foole" by John Donne (1572-1631) _______________________________________________ use-revolution mailing list [EMAIL PROTECTED] http://lists.runrev.com/mailman/listinfo/use-revolution
