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Intrusion and Type erasure

Intrusion and Type erasure

std.DoublyLinkedList works with Nodes.

Just

  • embed Node to you structs
  • use DoublyLinkedList functions

DoublyLinkedList does not care

  • what's the type of parent struct
  • whether structs in the list have the same type

Because Node already has pointers , DoublyLinkedList

  • does not need allocate wrappers for structs
  • uses existing pointers(links)

Terms:

  • Intrusion — the links are part of the struct
  • Type erasure — DoublyLinkedList operates on Node, not on the concrete type

Caller

  • follows its own rules
  • can get pointer to the parent struct
  • via @fieldParentPtr

This simple mechanism is the basis of Matryoshka.