Re: undo

[Vincent.Prunet@sophia.inria.fr (Vincent Prunet)]

=> Some tools may be updated at every modification and some tools may be updated
=> only once in a while.  For this reason, the variable may have to store
=> several different modification paths.  In this respect, having a function
=> ({variable}:undo variable) would not make much sense.

Guy Durrieu, Valerie, and I were thinking of a different function
which would take a path as second argument. Maybe we should call
this function {variable}:undo-modif or {variable}:apply-modif.

One can see in the documentation that {variable} functions enable
to change, insert or delete a subtree, and also to get
modifications (structured diffs) between 2 states of the tree. I
regret that there does not exist a function which would apply such
a modification to a variable exactly as if atomic modifications
were applied in sequence.

Valerie showed us a possible implementation for this function. 
Shouldn't we integrate this function in the code and documentation?

Vincent