Control group

New to the concepts? See Tools — PolyNode first.

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reset

pub fn reset(n: *PolyNode) void

• Clears intrusive link pointers (prev, next to null). Intrusive means the list pointers live inside your struct, not in a separate list node.

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is_linked

pub fn is_linked(n: *PolyNode) bool

• Returns true if the node has neighbours — prev or next is set.

• Not a membership test. std.DoublyLinkedList never sets the links of a list's only member, so a list of exactly one reports false.

• The !is_linked asserts inside Mbox.send, Pool.put, PolyHelper.destroy and PolyHelper.moveFromSlot catch the multi-element
  case and are blind for a list of one.

• To find out whether a list holds an item, ask the list. The insert asserts do — see Std compatibility.

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One place, one state — read-only ops

These operations never move a handle:

• tag checks
• typed casts
• @fieldParentPtr recovery

Read-only inspections of an existing node.

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