Re: Question over serialization
This is really a concept question. I think most of us know how to enable
backwards compatiblity. In other words a file saved in version 1, of our
app, can be opened in version two. This is relatively simple because version
2 is aware of version 1's data structure and so it can open it accordingly.
However what do u think would be the best way to open a version 2 document
in version 1? I know that MS word and lots of other apps can do this, so its
clearly do-able? My app has lots of different objects, all of which have
their own serialise methods. I use a CArchive from a file, and maybe my
understanding of the carchive is weak, but how do you know you've reached the
end of the archive that pertains to the problem.
Take the issue -
Version 1 - The CodeGuru object, saves these attributes.
Version 2 - The CodeGuru object, saves these attributes.
bool - saves extra bool for some new feature lets say.
Well if you read in the version 2 document in version 1, i assume you would
CString - read in fine
bool- read in fine
int- read in fine
int - read in fine
int - read in fine
this would be the end of the first code guru object so you start on the next.
CString - read in wrong because the next type would in fact be a bool.
Do you see what i mean? i hope i have explained this well. Does the
carchive have an end - of - this object flag? or do we as developers have to
Thanks really interested to see what people have to say on this
I have never used binary serialization. But if you use XML and your
(a) Supplies suitable defaults for missing tags
(b) Ignores tags it does not recognize
then you will automatically have both forward and backward compatiblity.
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