Different ways to implement 'dirty'-flag functionality
design-patterns
Solution
For my DAO I keep a copy of the original values as retrieved from the database. When I send it to be updated, I simply compare the original values with the current. It costs a little in processing but it is a lot better than having a dirty flag per property.
EDIT to further justify not having a dirty flag: if the property returns to its original value, there is no way to reflect that, the dirty flag continues dirty because the original value was lost.
Problem
Almost every programmer did it once in his life: setting some flag if a variable's value changed. There's always lots of properties and you want to keep track if something changed - in any property - in a specific property - or in some set of properties I'm interested in different ways to implement the "dirty-flag" functionality for the above situations, besides the standard object wide dirty flag being updated on each property change. There must be something better than putting "dirty = true" in each setter: it just looks ugly and is a tedious work.