Undo?
Mr. Jonse
Jonse at Theory.uni
Tue Oct 10 02:36:56 UTC 2017
I requiring an undo feature in my code. Rather than go the
regular route of using commands, I'm wondering if D can
facilitate an undo system quite easily?
We can think of an undo system in an app as a sort of recorder.
The traditional method is to use commands and inverse-commands.
By recording the commands one can "unwind" the program by
applying the inverse commands. The down side is that the app must
be written with this approach in mind.
Storing the complete state of the app is another way which some
apps use but usually it is too much data to store.
Since the only thing that one has to store from state of the app
to the next is the change in data long with creation and deletion
of the data, I think one could simplify the task?
Is it possible to write a generic system that records the the
entire state changes without much boilerplate?
I'm thinking that two types of attributes would work, one for
aggregates for creation and deletion of objects and one for
properties to handle the data changes. If D can be used to
automatically hook properties to have them report the changes to
the undo system and one can properly deal with object creation
and assignment, it might be a pretty sleek way to support undo.
Help appreciated!
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