Null Object Pattern

Kind: pattern

Layer: Design Patterns Core

Aliases: Null Object

Record: architecture:null-object-pattern

Severity: contextual

Scope: behavior, absence, default

Canonical: Ontology

A design pattern that represents absence with an object implementing the expected interface as a no-op.

Listed in Architecture principles, after Memento Pattern and before Finite State Machine.

Requires

• Shared Behavioral Interface

Reinforces

• Polymorphism
• Fail-Safe Defaults

Enables

• Null-Check Elimination

Conflicts with

• Null Semantics Drift

In tension with

• Silent No-Op Risk

Tensions

• Null Object Pattern / Silent No-Op Risk

Violated by

• Scattered Null Guards

Severity

• contextual

Category

• Behavioral Patterns

Linked from

• Anti-patterns
• SOLID / Object-Oriented Design
• Behavioral Patterns
• Severity levels
• The resolutions