M2compiler-V3/docs/summary_class-finish.md

Step: CLASS finished (sibling calls + init body)

Tag v3-class-finish. Suite 146/146; fixpoint OK (image 2,313,762 bytes).

Removes the last two implementable 230s in the Clarion class area (the third, multiple parents, stays a deliberate limitation).

Sibling-method calls

Inside a CLASS IMPLEMENTATION body, a bare method name is a call on THIS:

CLASS IMPLEMENTATION Acc;
  PROCEDURE Add(v : INTEGER);       BEGIN total := total + v END Add;
  PROCEDURE AddTwice(a, b : INTEGER);
  BEGIN Add(a); Add(b) END AddTwice;      (* sibling calls *)
END Acc;

• SymTab tracks the innermost open implementation (PushImplClass/ PopImplClass/CurImplClass); ClassImplRest pushes it.
• Design: when an identifier is not found in the ordinary scopes but the current implementation class has a method of that name, it binds the method, arms THIS as the receiver (QbeGen.ThisBase + ArmRecv), and marks a static (or virtual, if VIRTUAL) call.

Class BEGIN … END init body

A class's initialisation body now compiles and runs once at startup, as <Class>_init (registered in the same list as module init functions, called from main):

CLASS IMPLEMENTATION C;
  ...
BEGIN
  g := 41                 (* runs at startup *)
END C;

A body that references instance fields has no receiver and still reports 230 (class statics do not exist in V3).

Multiple parents — deliberate

CLASS Multi (A, B) (more than one parent) remains 230: the design is single inheritance only (docs/OOP.txt). showcase5.mod keeps that rejection under test.

Tests

• t_classsibling.mod (7): sibling calls.
• t_classinit.mod (42): the init body sets a global before main.
• t_class.mod promoted from a reject test to a run test (0).
• showcase5.mod still rejects (multiple parents).

Files

compiler/src/SymTab.def/.mod (implStk, PushImplClass/ PopImplClass/CurImplClass), compiler/src/M2.atg (ClassImplRest push/pop + init body, Design sibling-call branch), compiler/tests/{t_classsibling,t_classinit}.mod, compiler/run_tests.sh, docs/{features,OOP}.txt.