Editing Observer pattern (section)

===Uncoupled===
The observer pattern may be used in the absence of publish-subscribe, as when model status is frequently updated. Frequent updates may cause the view to become unresponsive (e.g., by invoking many [[painter's algorithm|repaint]] calls); such observers should instead use a timer. Instead of becoming overloaded by change message, the observer will cause the view to represent the approximate state of the model at a regular interval. This mode of observer is particularly useful for [[progress bar|progress bars]], in which the underlying operation's progress changes frequently.