Summary

Create C++20 module files for common_system as the foundation layer (Tier 0) of the unified system ecosystem.

Parent Epic

Part of #256 (C++20 Module Migration - Cross-System Preparation)

Prerequisites

• Result Header Consolidation ([REFACTOR] Consolidate Result<T> headers from 9 to 3 - C++20 Module preparation #255) - COMPLETED

Proposed Module Structure

// Primary module interface
export module kcenon.common;

export import kcenon.common.result;
export import kcenon.common.interfaces;
export import kcenon.common.di;
export import kcenon.common.patterns;

Module Partitions

File Structure

src/modules/
├── common.cppm              # Primary module interface
├── result.cppm              # Result<T> partition
├── interfaces.cppm          # Interfaces partition
├── di.cppm                  # DI partition
└── patterns.cppm            # Patterns partition

CMake Configuration

cmake_minimum_required(VERSION 3.28)
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_SCAN_FOR_MODULES ON)

add_library(kcenon_common)
target_sources(kcenon_common
    PRIVATE FILE_SET CXX_MODULES
    FILES
        src/modules/common.cppm
        src/modules/result.cppm
        src/modules/interfaces.cppm
        src/modules/di.cppm
        src/modules/patterns.cppm
)

Tasks

• Create module directory structure
• Create common.cppm primary interface
• Create result.cppm partition
• Create interfaces.cppm partition
• Create di.cppm partition
• Create patterns.cppm partition
• Update CMakeLists.txt for module support
• Verify no circular module dependencies
• Update all tests to use modules
• Performance benchmark (compile time)
• Update documentation

Acceptance Criteria

• Module builds successfully with CMake 3.28+
• All existing tests pass with module
• No circular dependencies between partitions
• Header-based build still works (transition period)
• Performance not regressed

Migration Timeline

This is Phase 2 work (Release N+3) per EPIC #256:

• Phase 1 (Refactoring) must be complete first
• All dependent systems wait for this module

Related

• C++20 Module Migration Epic ([EPIC] C++20 Module Migration - Cross-System Preparation #256)
• Result Header Consolidation ([REFACTOR] Consolidate Result<T> headers from 9 to 3 - C++20 Module preparation #255) - prerequisite completed