{
  "id": "programming.objects.constructor-returns-object",
  "uri": "https://open-misconceptions.github.io/miscon-data/m/programming.objects.constructor-returns-object",
  "uuid": "82998d6e-dc24-425a-984e-e60d6a3b1de6",
  "version": "0.1.1",
  "status": "draft",
  "trust": "low",
  "title": "A constructor must return the object",
  "statement": "A constructor creates the object and has to return it at the end, so a constructor without a return statement produces nothing.",
  "kind": "overgeneralization",
  "domain": "programming.objects",
  "about": [
    {
      "scheme": "Miscon",
      "uri": "https://open-misconceptions.github.io/miscon-data/c/programming.objects.constructor"
    }
  ],
  "level_band": [
    "secondary",
    "undergraduate"
  ],
  "locale": "en",
  "evidence_patterns": [
    {
      "item_shape": "write a constructor",
      "signature": "adds return this (or return self) at the end, or a return type to the constructor header",
      "example": {
        "item": "Write a constructor for Point that stores x and y.",
        "expected": "Point(int x, int y) { this.x = x; this.y = y; }",
        "response": "Point Point(int x, int y) { this.x = x; this.y = y; return this; }"
      }
    }
  ],
  "discriminators": {
    "vs_slip": "A slip is a stray return removed when noticed. The belief is stated ('otherwise you don't get the object back') and the learner also expects new Point(1, 2) to be 'empty' without it."
  },
  "relations": {
    "conflicts_with": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.objects.constructor",
        "label": "A constructor initialises an object the runtime has already created"
      }
    ],
    "resolved_by": [
      {
        "external": "https://open-misconceptions.github.io/miscon-data/c/programming.objects.constructor",
        "label": "A constructor initialises an object the runtime has already created"
      }
    ]
  },
  "alignments": [
    {
      "scheme": "progmiscon",
      "code": "Java/ConstructorReturnsObject",
      "uri": "https://progmiscon.org/misconceptions/Java/ConstructorReturnsObject",
      "relation": "close-match"
    },
    {
      "scheme": "progmiscon",
      "code": "Python/InitReturnsObject",
      "uri": "https://progmiscon.org/misconceptions/Python/InitReturnsObject",
      "relation": "close-match"
    }
  ],
  "provenance": {
    "sources": [
      {
        "type": "inventory",
        "citation": "Chiodini, L., Moreno Santos, I., Gallidabino, A., Tafliovich, A., Santos, A. L., & Hauswirth, M. (2021). A curated inventory of programming language misconceptions. In Proceedings of the 26th ACM Conference on Innovation and Technology in Computer Science Education (ITiCSE '21), 380-386.",
        "doi": "10.1145/3430665.3456343",
        "url": "https://progmiscon.org/",
        "note": "Inventory consulted for the misconception name and scope only; progmiscon publishes no licence for its text, so Open Misconceptions' statements and examples are written independently."
      },
      {
        "type": "paper",
        "citation": "Ragonis, N., & Ben-Ari, M. (2005). A long-term investigation of the comprehension of OOP concepts by novices. Computer Science Education, 15(3), 203-221.",
        "doi": "10.1080/08993400500224310",
        "note": "Novice comprehension of constructors and object creation."
      }
    ],
    "origin": "llm-drafted",
    "notes": "Drafted from the cited literature for the Open Misconceptions seed pack; statement, examples and discriminators are original text. Awaiting maintainer review."
  },
  "history": {
    "changelog": [
      {
        "version": "0.1.1",
        "date": "2026-09-05",
        "change": "Schema 0.2 migration: about/alignments carry a free-string scheme (corestandards.org URLs relabelled CCSS where present); trust computed from reviews[] (none yet, so low); no change to the statement or evidence."
      }
    ]
  },
  "license": "CC-BY-4.0"
}