Peter Dimov wrote:
Joel de Guzman wrote:
Peter Dimov wrote:
I can't help but wonder: if some parts of your v1 format are so completely redundant as to allow you to reconstruct the original data even if you skip them, what was the point of writing them in the first place? Here's one scenario (I'm sure there are others): Your class uses a 3rd party library called Y. Later, you decide to replace it with a better engine using a library called Z.
Still not getting it. Do you have an example?
That was the example ;)... Ok let me see if I can clarify... With version 1 you have a class A with this structure: class A { W, w, X x; Y rep; }; Now with version 2, you want to use a new engine to replace Y: class A { W, w, X x; Z rep; }; Z is so different from Y that it does not need any of its data. It is also plausible that W,X,Y and Z get some data from other external sources. So, in effect, Z starts with a default data and gets filled as the app runs. Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net