{
  "code": null,
  "collection": "architecture",
  "href": "https://banes-lab.com/ontology#architecture-composite-pattern",
  "id": "composite-pattern",
  "kind": "pattern",
  "layer": {
    "href": "https://banes-lab.com/ontology/schema#layer-design-patterns-core",
    "json": "https://banes-lab.com/json/records/layer/design-patterns-core",
    "label": "Design Patterns Core",
    "markdown": "https://banes-lab.com/records/layer/design-patterns-core.md",
    "ref": "layer:design-patterns-core"
  },
  "name": "Composite Pattern",
  "ref": "architecture:composite-pattern",
  "relations": [
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology/lexicon#lexicon-uniform-component-interface",
          "json": "https://banes-lab.com/json/records/lexicon/uniform-component-interface",
          "label": "Uniform Component Interface",
          "markdown": "https://banes-lab.com/records/lexicon/uniform-component-interface.md",
          "ref": "lexicon:uniform-component-interface"
        }
      ],
      "relation": "requires"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology#architecture-uniform-interface",
          "json": "https://banes-lab.com/json/records/architecture/uniform-interface",
          "label": "Uniform Interface",
          "markdown": "https://banes-lab.com/records/architecture/uniform-interface.md",
          "ref": "architecture:uniform-interface"
        },
        {
          "href": "https://banes-lab.com/ontology#architecture-open-closed",
          "json": "https://banes-lab.com/json/records/architecture/open-closed",
          "label": "Open/Closed Principle (OCP)",
          "markdown": "https://banes-lab.com/records/architecture/open-closed.md",
          "ref": "architecture:open-closed"
        }
      ],
      "relation": "reinforces"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology/lexicon#lexicon-recursive-composition",
          "json": "https://banes-lab.com/json/records/lexicon/recursive-composition",
          "label": "Recursive Composition",
          "markdown": "https://banes-lab.com/records/lexicon/recursive-composition.md",
          "ref": "lexicon:recursive-composition"
        },
        {
          "href": "https://banes-lab.com/ontology/lexicon#lexicon-leaf-composite-transparency",
          "json": "https://banes-lab.com/json/records/lexicon/leaf-composite-transparency",
          "label": "Leaf/Composite Transparency",
          "markdown": "https://banes-lab.com/records/lexicon/leaf-composite-transparency.md",
          "ref": "lexicon:leaf-composite-transparency"
        }
      ],
      "relation": "enables"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology/lexicon#lexicon-leaf-vs-container-special-casing",
          "json": "https://banes-lab.com/json/records/lexicon/leaf-vs-container-special-casing",
          "label": "Leaf-vs-Container Special-Casing",
          "markdown": "https://banes-lab.com/records/lexicon/leaf-vs-container-special-casing.md",
          "ref": "lexicon:leaf-vs-container-special-casing"
        }
      ],
      "relation": "conflicts-with"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology#architecture-type-safety",
          "json": "https://banes-lab.com/json/records/architecture/type-safety",
          "label": "Type Safety",
          "markdown": "https://banes-lab.com/records/architecture/type-safety.md",
          "ref": "architecture:type-safety"
        }
      ],
      "relation": "tensions-with"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology/schema#tension-composite-pattern-type-safety",
          "json": "https://banes-lab.com/json/records/tension/composite-pattern-type-safety",
          "label": "Composite Pattern / Type Safety",
          "markdown": "https://banes-lab.com/records/tension/composite-pattern-type-safety.md",
          "ref": "tension:composite-pattern-type-safety"
        }
      ],
      "relation": "tensions"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology/lexicon#lexicon-leaf-vs-container-special-casing",
          "json": "https://banes-lab.com/json/records/lexicon/leaf-vs-container-special-casing",
          "label": "Leaf-vs-Container Special-Casing",
          "markdown": "https://banes-lab.com/records/lexicon/leaf-vs-container-special-casing.md",
          "ref": "lexicon:leaf-vs-container-special-casing"
        }
      ],
      "relation": "violated-by"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology/schema#vocabulary-severity-recommended",
          "json": "https://banes-lab.com/json/records/vocabulary/severity-recommended",
          "label": "recommended",
          "markdown": "https://banes-lab.com/records/vocabulary/severity-recommended.md",
          "ref": "vocabulary:severity-recommended"
        }
      ],
      "relation": "severity"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology#architecture-category-structural-patterns",
          "json": "https://banes-lab.com/json/records/architecture-category/structural-patterns",
          "label": "Structural Patterns",
          "markdown": "https://banes-lab.com/records/architecture-category/structural-patterns.md",
          "ref": "architecture-category:structural-patterns"
        }
      ],
      "relation": "category"
    },
    {
      "links": [
        {
          "href": "https://banes-lab.com/ontology#architecture-category-contracts-interfaces-compatibility",
          "json": "https://banes-lab.com/json/ontology/principles/architecture-category-contracts-interfaces-compatibility",
          "label": "Contracts / Interfaces / Compatibility",
          "markdown": "https://banes-lab.com/ontology/principles/architecture-category-contracts-interfaces-compatibility.md",
          "ref": "chapter:/ontology#architecture-category-contracts-interfaces-compatibility"
        },
        {
          "href": "https://banes-lab.com/ontology#architecture-category-solid-object-oriented-design",
          "json": "https://banes-lab.com/json/ontology/principles/architecture-category-solid-object-oriented-design",
          "label": "SOLID / Object-Oriented Design",
          "markdown": "https://banes-lab.com/ontology/principles/architecture-category-solid-object-oriented-design.md",
          "ref": "chapter:/ontology#architecture-category-solid-object-oriented-design"
        },
        {
          "href": "https://banes-lab.com/ontology#architecture-category-schema-canonical-data-semantics",
          "json": "https://banes-lab.com/json/ontology/principles/architecture-category-schema-canonical-data-semantics",
          "label": "Schema / Canonical Data / Semantics",
          "markdown": "https://banes-lab.com/ontology/principles/architecture-category-schema-canonical-data-semantics.md",
          "ref": "chapter:/ontology#architecture-category-schema-canonical-data-semantics"
        },
        {
          "href": "https://banes-lab.com/ontology/lexicon#lexicon-category-structural-patterns",
          "json": "https://banes-lab.com/json/ontology/lexicon/lexicon-category-structural-patterns",
          "label": "Structural Patterns",
          "markdown": "https://banes-lab.com/ontology/lexicon/lexicon-category-structural-patterns.md",
          "ref": "chapter:/ontology/lexicon#lexicon-category-structural-patterns"
        },
        {
          "href": "https://banes-lab.com/ontology/schema#the-vocabulary-severity",
          "json": "https://banes-lab.com/json/ontology/schema/the-vocabulary-severity",
          "label": "Severity levels",
          "markdown": "https://banes-lab.com/ontology/schema/the-vocabulary-severity.md",
          "ref": "chapter:/ontology/schema#the-vocabulary-severity"
        },
        {
          "href": "https://banes-lab.com/ontology/schema#the-resolutions",
          "json": "https://banes-lab.com/json/ontology/schema/the-resolutions",
          "label": "The resolutions",
          "markdown": "https://banes-lab.com/ontology/schema/the-resolutions.md",
          "ref": "chapter:/ontology/schema#the-resolutions"
        }
      ],
      "relation": "linked-from"
    }
  ],
  "summary": "A design pattern that gives leaves and groups one interface, so a tree is traversed without checking which kind each node is.",
  "siblings": {
    "next": {
      "href": "https://banes-lab.com/ontology#architecture-flyweight-pattern",
      "json": "https://banes-lab.com/json/records/architecture/flyweight-pattern",
      "label": "Flyweight Pattern",
      "markdown": "https://banes-lab.com/records/architecture/flyweight-pattern.md",
      "ref": "architecture:flyweight-pattern"
    },
    "previous": {
      "href": "https://banes-lab.com/ontology#architecture-decorator-pattern",
      "json": "https://banes-lab.com/json/records/architecture/decorator-pattern",
      "label": "Decorator Pattern",
      "markdown": "https://banes-lab.com/records/architecture/decorator-pattern.md",
      "ref": "architecture:decorator-pattern"
    }
  },
  "up": {
    "href": null,
    "json": "https://banes-lab.com/json/api/records/architecture",
    "label": "Architecture principles",
    "markdown": "https://banes-lab.com/api/records/architecture.md",
    "ref": "api:records/architecture"
  },
  "aliases": [],
  "exemplar": {
    "after": "interface FooComponent { total(): number; }\nclass FooLeaf implements FooComponent {\n  constructor(private readonly value: number) {}\n  total() { return this.value; }\n}\nclass FooGroup implements FooComponent {\n  constructor(private readonly children: readonly FooComponent[]) {}\n  total() { return this.children.reduce((sum, child) => sum + child.total(), 0); }\n}",
    "before": "function totalFoo(item: Foo | FooGroup): number {\n  if (\"children\" in item) return item.children.reduce((sum, child) => sum + totalFoo(child), 0);\n  return item.value;\n}",
    "lang": "ts",
    "medium": "code"
  },
  "formedBy": null,
  "scope": [
    "structure",
    "tree",
    "hierarchy"
  ],
  "severity": "recommended"
}