Observer
E173618
Observer is a behavioral design pattern that defines a one-to-many dependency between objects so that when one object changes state, all its dependents are automatically notified and updated.
All labels observed (1)
| Label | Occurrences |
|---|---|
| Observer canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T1531331 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: Observer Context triple: [Design Patterns: Elements of Reusable Object-Oriented Software, describesPattern, Observer]
-
A.
Voyeur
"Voyeur" is a 1981 synth-driven pop song by American singer Kim Carnes, known for its dark, edgy style and follow-up success to her hit "Bette Davis Eyes."
-
B.
The New Observer
The New Observer was the original name of the British newspaper that later became known as The Sunday Times.
-
C.
Wanderer
Wanderer is Sterling Hayden’s autobiographical memoir, renowned for its candid reflections on his Hollywood career, seafaring life, and political disillusionment.
-
D.
Storyteller
"Storyteller" is a seminal work of the Native American Renaissance that blends traditional Indigenous oral narratives with contemporary literary forms to explore Native identity and cultural continuity.
-
E.
Beschermer
Beschermer was a Dutch warship that served in the late 18th century and was captured by the British Royal Navy during the Battle of Camperdown in 1797.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: Observer Target entity description: Observer is a behavioral design pattern that defines a one-to-many dependency between objects so that when one object changes state, all its dependents are automatically notified and updated.
-
A.
Voyeur
"Voyeur" is a 1981 synth-driven pop song by American singer Kim Carnes, known for its dark, edgy style and follow-up success to her hit "Bette Davis Eyes."
-
B.
The New Observer
The New Observer was the original name of the British newspaper that later became known as The Sunday Times.
-
C.
Wanderer
Wanderer is Sterling Hayden’s autobiographical memoir, renowned for its candid reflections on his Hollywood career, seafaring life, and political disillusionment.
-
D.
Storyteller
"Storyteller" is a seminal work of the Native American Renaissance that blends traditional Indigenous oral narratives with contemporary literary forms to explore Native identity and cultural continuity.
-
E.
Beschermer
Beschermer was a Dutch warship that served in the late 18th century and was captured by the British Royal Navy during the Battle of Camperdown in 1797.
- F. None of above. chosen
Statements (48)
| Predicate | Object |
|---|---|
| instanceOf |
behavioral design pattern
ⓘ
design pattern ⓘ |
| advantage |
facilitates reuse of subjects and observers independently
ⓘ
subject does not need to know concrete observer classes ⓘ supports dynamic registration and removal of observers ⓘ |
| alternativeName |
Dependents pattern
ⓘ
NSNotificationCenter ⓘ
surface form:
Listener pattern
Publish–Subscribe pattern ⓘ |
| appearsIn | Design Patterns: Elements of Reusable Object-Oriented Software ⓘ |
| belongsTo |
Gang of Four design pattern
ⓘ
surface form:
Gang of Four design patterns
|
| commonIn |
.NET event and delegate model
ⓘ
GUI frameworks ⓘ Java event model ⓘ reactive programming libraries ⓘ |
| defines | one-to-many dependency between objects ⓘ |
| definesResponsibility |
Observer updates in response to notifications
ⓘ
Subject maintains list of observers ⓘ Subject notifies observers of state changes ⓘ |
| describedBy |
Erich Gamma
ⓘ
John Vlissides ⓘ Ralph Johnson NERFINISHED ⓘ Richard Helm ⓘ |
| disadvantage |
can cause cascading updates and performance issues
ⓘ
can lead to many spurious updates ⓘ notification order may be undefined ⓘ |
| formalDefinition | defines a one-to-many dependency so that when one object changes state, all its dependents are notified and updated automatically ⓘ |
| involvesRole |
ConcreteObserver
ⓘ
ConcreteSubject ⓘ Observer ⓘ Subject ⓘ |
| keyOperation |
attach observer
ⓘ
detach observer ⓘ notify observers ⓘ |
| purpose | to notify dependents automatically when subject state changes ⓘ |
| relatedTo |
Mediator pattern
ⓘ
Model-View-Controller ⓘ
surface form:
Model–View–Controller architectural pattern
Singleton pattern ⓘ |
| supports |
broadcast communication
ⓘ
event-driven programming ⓘ loose coupling between subject and observers ⓘ model–view separation ⓘ |
| typicalImplementationDetail |
observers register via an interface
ⓘ
subject calls update method on observers ⓘ subject keeps a collection of observer references ⓘ |
| usedFor |
implementing data binding
ⓘ
implementing event listeners in GUIs ⓘ implementing model–view–controller (MVC) ⓘ notification systems ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: Observer Description of subject: Observer is a behavioral design pattern that defines a one-to-many dependency between objects so that when one object changes state, all its dependents are automatically notified and updated.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.