Impact Analysis Before Modifying Shared Methods

When deciding whether to add new fields to a shared transformation method (like toArray() or custom serializers), always check all usages first to understand the blast radius.

The decision:
Should you add fields to a shared method, or add them at the call site?

Step 1: Find all usages

rg "MyClass::toArray\(\)" app/ --type php -B 2 -A 2

Step 2: Analyze each consumer

• Does it expect specific keys only?
• Will extra keys cause issues?
• Is it part of an API contract?

Example scenario:

// Shared method
public static function toSettings(Product $product): array
{
    return [
        'name' => $product->name,
        'price' => $product->price,
        // Should 'markup' go here or at call site?
    ];
}

// Consumer 1: API endpoint (wants markup)
// Consumer 2: Alert notification (only reads price, ignores extra)
// Consumer 3: Report transformer (spreads array into larger struct)

Decision criteria:

• If ALL consumers need it → add to shared method
• If ONE consumer needs it → add at call site
• If it breaks an API contract → versioned endpoint or call-site addition

Pro tip: Use git grep or rg (ripgrep) to search, not IDE search—catches dynamic calls and string references.