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14 lines
460 B
Markdown
14 lines
460 B
Markdown
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# Observer
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## Purpose
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To implement a publish/subscribe behaviour to an object, whenever a "Subject" object changes it's state, the attached
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"Observers" will be notified. It is used to shorten the amount of coupled objects and uses loose coupling instead.
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## Examples
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* a message queue system is observed to show the progress of a job in a GUI
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## Note
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PHP already defines two interfaces that can help to implement this pattern: SplObserver and SplSubject.
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