Smalltalk ReferenceStream has problems with new instance variables?

Question

In Pharo Smalltalk I'm using ReferenceStream to serialise a list of objects -- here's the class definition of the objects I'm serialising:

Object subclass: #Task
instanceVariableNames: 'title notes list project dateNextAction dateCreated dateCompleted importance selected'
classVariableNames: 'Database'
poolDictionaries: ''
category: 'ToDo'

I'm using the SMFileDatabase method described here: http://book.seaside.st/book/advanced/persistency/image-based-persistency

This has been working well, and it's been nice not to have to use a database for my prototype app.

Howevere, here's the problem: when I add a new instance variable person to Task the load from ReferenceStream breaks:

Object subclass: #Task
instanceVariableNames: 'title notes list project person dateNextAction dateCreated dateCompleted importance selected'
classVariableNames: 'Database'
poolDictionaries: ''
category: 'ToDo'

It seems to not spot the new variable, and load the values into the wrong slots, so person takes the value of dateNextAction, dateNextAction takes dateCreated and so on.

How can I stop this happening?

I've got it working by placing the new variable at the end of the list, but I'd like to group variables by type.

Answer 1

ReferenceStream is not supported anymore and has been deleted in Pharo 2.0. You should use Fuel which is well written, well documented, well tested and very fast. http://rmod.lille.inria.fr/web/pier/software/Fuel