13.5. Fallback Example

This is what happens when a fallback is implemented: 
Person( age == 50 )

// If Person.getAge() does not exists, this falls back to:
Person( age() == 50 )
This is what it looks like as a nested property: 
Person( address.houseNumber == 50 )

// this is the same as:
Person( getAddress().getHouseNumber() == 50 )

Warning

In a stateful session, care should be taken when using nested accessors as the Working Memory is not aware of any of the nested values and does not know when they change. Consider them immutable while any of their parent references are inserted into the Working Memory. If you wish to modify a nested value you should mark all of the outer facts as updated. In the above example, when the houseNumber changes, any Person with that Address must be marked as updated.
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