[Q] Backward compatible code
giovanni.giorgi at siforge.org
Wed Dec 1 15:54:30 UTC 2004
As fas as I know
there is some support on Object to reload "obsolete instances" and
to convert them forard new instances.
Squeak can detect changes in the instance variables of an object when it
is loaded, as far as I know.
Full compatibility between major Squeak image revision is in general a
I will encourage you to think about what do you really need: the
solution in the general case is a hard challenge :) and probably do not
need it :)
SIXX is a good export/import tool, for instance: and has done the work
for a lot of my personal project :)
Lic. Edgar J. De Cleene ha scritto in data 01/12/2004 14.58:
>I trying to build a Help system for Squeak, and I saving "cards" as
>compressed objects (and saving that to somewhere for later use).
>Works as long how images are compatibles.
>Backwards compatibility is a long talked issue in Computers, so I wish to
>know how could be a Smalltalk / Squeak smart solution .
>In Squeak3.8gamma-6475.image I have
>This class provides the abstract super class for the original String (that
>represents an array of 8-bit Characters) and MultiString (that represents an
>array of 32-bit MultiCharacters). In the similar manner of LargeInteger
>and SmallInteger, those subclasses are chosen accordingly for a string;
>namely as long as the system can figure out so, the String is used to
>represent the given string.
>But older images don't know and you get a PopUp with guessing.
>Some clues ? Could one object know what Squeak versions was originated ?
Giovanni Giorgi http://www.squeak.org
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