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REFANY.md

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REFANY

Universal reference type. Can hold any REF value regardless of its target type. Requires --m2plus.

Syntax

VAR x: REFANY;

Notes

  • Any REF T or OBJECT value can be assigned to a REFANY variable.
  • REFANY values carry a runtime type descriptor (M2_TypeDesc) stored in a hidden header prepended to the allocation. This identifies the concrete type and its parent chain.
  • Use TYPECASE to dispatch on the runtime type of a REFANY value.
  • REFANY cannot be dereferenced directly -- you must narrow it to a specific REF type via TYPECASE first.
  • NIL is a valid REFANY value. TYPECASE handles it safely (falls through to ELSE).
  • Useful for building heterogeneous data structures such as collections that store mixed types.
  • REFANY can be used as a formal parameter type.

Example

TYPE
  IntRef = REF INTEGER;
  StrRef = REF ARRAY [0..31] OF CHAR;
VAR
  any: REFANY;
  ir: IntRef;
BEGIN
  NEW(ir);
  ir^ := 10;
  any := ir;
  TYPECASE any OF
    IntRef (v):
      WriteInt(v^, 0); WriteLn
  | StrRef:
      WriteString("a string"); WriteLn
  END;
END RefAnyDemo.