Value object
A value object is an object whose meaning and equality derive from its attribute values rather than an independent identity, typically with immutable state.
Unit Testing Principles, Practices, and Patterns
A value object is an immutable object identified solely by its content rather than by an individual identity.
- How it is used
- Guides dependency substitution and output-based testing by separating immutable values from mutable state.
- How deep it goes
- Defines identity and immutability, then shows .NET equality implementation; it stops short of broader construction guidance.
- Examples
- Uses the integer 5, Product.Shampoo, FileUpdate, and audit-file instructions as concrete value examples.
- What you can do after
- Apply value equality to simplify output assertions and avoid substituting immutable dependencies with test doubles.
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Java Persistence with Spring Data and Hibernate epub
A developer-defined value type is an application-defined class whose instances are identified by their values rather than independent persistent identity.
- How it is used
- Models application-defined data that belongs to an entity rather than requiring independently identified persistence.
- How deep it goes
- Defines identity and lifecycle rules, then follows embeddable components into table layout and save/delete behavior; it does not specify equality-method implementations.
- Examples
- Contrasts shared and separately owned addresses, then places home and billing addresses in one user table row.
- What you can do after
- Apply it via JPA embeddable components when data has one owner and needs no independent persistent identity.
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The Joy of JavaScript
An immutable object whose equality and identity are determined by its attribute values rather than by a stable external identifier.
- How it is used
- Represents domain values such as money, dates, points, lines, and decimals within composable application code.
- How deep it goes
- Defines design rules and demonstrates JavaScript freezing, sealing, equality, arithmetic, and primitive conversion.
- Examples
- Uses Money, DateTime, Point, Line, Decimal, coordinate mutation, and currency-specific arithmetic examples.
- What you can do after
- Build it from scratch as a sealed, frozen JavaScript object with value-based equality and composable operations.
Related concepts
- immutable collectionkind of · An immutable collection is a collection whose membership and contents cannot be changed after creation.
- entitycontrasts with · An entity is a distinct, identifiable person, object, event, or concept represented as a unit in a data, software, or semantic model.
- valueuses · A value is the content, quantity, information, or worth attributed to an entity, property, expression, or outcome.
- Java recordproduced by · A Java record is a restricted class declaration for representing data with a fixed set of components and compiler-derived members such as constructors, accessors, and object methods.
- monitorcontrasts with · A monitor is an object-associated synchronization mechanism that provides mutual exclusion and coordinates thread waiting and notification.
- @Entitycontrasts with · The @Entity annotation is a Jakarta Persistence annotation that declares a Java class as a persistent entity mapped to stored data.
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