hakorune/docs/development/current/phase_9_78e_summary.md

Phase 9.78e: Dynamic Method Dispatch Implementation Summary

Status: Historical summary（Phase 9.78e 実装レポート）
Note: 現在の設計・実装状況は最新の docs/development/architecture/ / docs/development/roadmap/ を正とし、このファイルは当時の実装状態の記録としてのみ参照してください。

🎯 Overview

Phase 9.78e aimed to implement dynamic method dispatch through the call_method trait method to unify method calling across all Box types.

✅ Completed Tasks

1. NyashBox Trait Enhancement

• Added call_method to the NyashBox trait in src/box_trait.rs
• Default implementation returns MethodNotFound error
• Signature: fn call_method(&mut self, method_name: &str, args: Vec<NyashValue>) -> Result<NyashValue, RuntimeError>

2. StringBox Implementation

• Implemented call_method in src/boxes/string_box.rs
• Supports all StringBox methods:
  • type_name(), equals(), length()
  • concat(), split(), toUpperCase(), toLowerCase()
  • trim(), indexOf(), replace(), charAt(), substring()
• Includes argument validation and proper error handling

3. InstanceBox Implementation

• Implemented call_method in src/instance_v2.rs with delegation pattern:
  1. First checks user-defined methods
  2. Delegates to inner box for builtin methods
  3. Handles InstanceBox-specific methods (getField, setField, hasMethod)
• Enables transparent method calls on wrapped builtin boxes

4. Error Type Updates

• Added new RuntimeError variants:
  • MethodNotFound { method_name: String, type_name: String }
  • FieldNotFound { field_name: String, class_name: String }

5. Interpreter Integration (Partial)

• Added call_method integration in src/interpreter/expressions/calls.rs
• Implemented type conversion logic for Box to NyashValue
• Added debug output for tracking method dispatch flow

🚧 Challenges Encountered

1. Type Conversion Complexity

• Converting between Box<dyn NyashBox>, Arc<Mutex<dyn NyashBox>>, and NyashValue
• Current workaround: Direct type-based conversion for basic types

2. Binary Compilation Issues

• Several unrelated compilation errors in the binary prevent full testing
• Library builds successfully with call_method implementation

3. Architecture Considerations

• The current Box/NyashValue dual system creates friction
• Future consideration: Unified value representation system

📋 Test Results

• Basic StringBox creation and string operations work correctly
• Method calls currently fall back to legacy dispatch system
• Call_method infrastructure is in place but needs full integration

🔮 Next Steps

Immediate Tasks:

1. Fix binary compilation errors to enable full testing
2. Complete NyashValue/Box type conversion helpers
3. Implement call_method for remaining builtin Box types

Long-term Improvements:

1. Consider unified value representation to simplify type conversions
2. Optimize method dispatch performance
3. Add comprehensive test coverage for all Box types

💡 Key Insights

• The delegation pattern in InstanceBox successfully enables method calls on wrapped boxes
• Dynamic dispatch through call_method provides a clean abstraction for method calling
• Type conversion between the Box trait system and NyashValue remains a key challenge

📝 Code Locations

• Trait definition: src/box_trait.rs:124-130
• StringBox impl: src/boxes/string_box.rs:160-313
• InstanceBox impl: src/instance_v2.rs:197-263
• Interpreter integration: src/interpreter/expressions/calls.rs:230-288

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Phase 9.78e establishes the foundation for unified method dispatch across all Nyash Box types, with the core infrastructure successfully implemented and ready for expanded integration.