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Re: Treating an object as a structure [message #65487 is a reply to message #65432]

Fri, 06 March 2009 14:36

JDS
Messages: 94
Registered: March 2009

Member

I use this technique a lot:

snapshot=create_struct(NAME=obj_class(self))

or simply

snapshot={MYCLASS}
struct_assign,self,snapshot

later apply snapshot:

struct_assign,snapshot,self

This allows me to make snapshots of object data for the purpose of
undoing changes, or examining how it was at a certain point in time.
Keep a pointer to a list of these, and you have multiple undo. Add a
text phrase when snapshotting ("Frobnoid change") and you can
advertise "Undo Forbnoid change" and so on.

The lack of garbage collection starts getting painful at this point
though (since older versions could refer to data newer versions have
deleted).

Remember that snapshots of heap pointers (at whatever level in the
heirarchy) are not immutable. If you want a deep copy, you can use
the save/restore trick, first calling the new HEAP_NOSAVE routine on
items you won't need a deep copy of. Or you can simply replicate
certain heap data by hand (new=ptr_new(*old)). This reminds me that
we're still lacking deep copy capability without hitting the disk.

JD

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[Message index]

		Treating an object as a structure By: natha on Wed, 04 March 2009 12:20
		Re: Treating an object as a structure By: JDS on Fri, 06 March 2009 14:36
		Re: Treating an object as a structure By: natha on Thu, 05 March 2009 08:05
		Re: Treating an object as a structure By: Michael Galloy on Thu, 05 March 2009 08:01
		Re: Treating an object as a structure By: David Fanning on Wed, 04 March 2009 16:52
		Re: Treating an object as a structure By: natha on Wed, 04 March 2009 16:35
		Re: Treating an object as a structure By: natha on Wed, 04 March 2009 16:30
		Re: Treating an object as a structure By: David Fanning on Wed, 04 March 2009 15:54

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