Undo?

[Jesse Phillips]

On Thursday, 12 October 2017 at 02:18:49 UTC, Mr. Jonse wrote:
> A simple(incomplete) undo system.

I'd think that for D you'd want to do type wrapping where a new 
type is created which saves changes and can manage an Undo tree.

     __gshared Data data = new Data();
     auto undoable = Undo!data

     undoable.x = 5;
     assert(data.x == 5);

     undoable.undo();
     assert(data.x == 0);
     undoable.redo();
     assert(data.x == 5);

This would be done by monitoring the members which contain 
storage, available with:
https://dlang.org/phobos/std_traits.html#Fields

This is of course specific to a single object and plan for 
handling order across multiple objects along with creating an 
"Edit" where many data points could change and be undone with a 
single undo.