pardeike-Harmony/docs/infix/04-parameter-binding.md

Parameter binding: reuse and extend

Principle

Do not invent a new binder. Extend the existing injection resolver with a context flag: Outer vs Inner.

Binding sources

• Inner context
  • __instance → captured instance local for this call site.
  • Inner arg names → captured arg locals by name/position.
  • __result → the infix result local for this call site.
  • __args (optional later) → array from captured arg locals.
• Outer context (when name starts with o_)
  • Drop o_ and resolve using the current outer method resolver:
    • __instance, __args, arguments by name or index,
    • ___field, __state, __exception, outer __result if present.
• Outer locals
  • _var → load/address original outer local slot.
• Synthetic locals
  • _var → declare once per outer method; share between inner pre/post.

Ref/out handling

• If a patch parameter is by‑ref:
  • Provide ldloca for a value local, or the captured managed pointer local for by‑ref arguments.
• Result passthrough (optional):
  • If an inner postfix returns the same type as the inner result and takes it as first parameter, treat return as new __result.

Keep the emitted IL paths identical to existing binder behavior where possible. Only the source of values changes by context.