Scattered Concerns

Description

What does it look like?

• Logging logic and configuration access are written inconsistently across the codebase
• Each part of the system logs messages or loads config values in its own way, lacking consistency
• Implementation of logs and configs tends to vary depending on the developer

Why is it a problem?

• Low maintainability and poor reusability
• When log format or destination needs to change, the impact is widespread
• Incorrect config access or repeated loading may lead to performance issues and bugs

Bad Example of the Anti-pattern

TypeScript

// あちこちで Logger や設定を直接扱っている
class OrderService {
  createOrder(orderId: string) {
    console.log(`[OrderService] 注文作成: ${orderId}`); // 直書きログ
    const debugMode = process.env.DEBUG_MODE === "true"; // 設定の直接参照
    if (debugMode) {
      console.log(`[DEBUG] 注文詳細: ${orderId}`);
    }
  }
}

class UserService {
  createUser(name: string) {
    console.log(`[UserService] ユーザー作成: ${name}`);
  }
}

PHP

<?php

class OrderService {
  public function createOrder(string $orderId): void {
    echo "[OrderService] 注文作成: {$orderId}\n"; // 直書きログ

    $debugMode = getenv("DEBUG_MODE") === "true"; // 設定の直接参照
    if ($debugMode) {
      echo "[DEBUG] 注文詳細: {$orderId}\n";
    }
  }
}

class UserService {
  public function createUser(string $name): void {
    echo "[UserService] ユーザー作成: {$name}\n"; // 直書きログ
  }
}

// 環境変数設定（実行前に CLI などで設定）
// putenv("DEBUG_MODE=true");

$orderService = new OrderService();
$orderService->createOrder("order-123");

$userService = new UserService();
$userService->createUser("hiroshi");

Python

import os

class OrderService:
    def create_order(self, order_id: str):
        print(f"[OrderService] 注文作成: {order_id}")  # 直書きログ

        debug_mode = os.environ.get("DEBUG_MODE") == "true"  # 設定の直接参照
        if debug_mode:
            print(f"[DEBUG] 注文詳細: {order_id}")

class UserService:
    def create_user(self, name: str):
        print(f"[UserService] ユーザー作成: {name}")  # 直書きログ

# 実行例
# os.environ["DEBUG_MODE"] = "true"

order_service = OrderService()
order_service.create_order("order-123")

user_service = UserService()
user_service.create_user("hiroshi")

Issues:

• Direct use of console.log() → Must update every log when the format changes
• Direct access to process.env → No centralized configuration management
• Responsibility is scattered and reuse is difficult

Refactoring by Pattern

Design patterns that can address this

Pattern	Overview	Main Refactoring Approach
Singleton	Restrict instance to one across the application	Manage logs and configs as shared state
Facade	Provide a simplified API for logging and config access	Create a unified interface for use