Getting Started

Run composer require --dev ramsey/composer-repl to install it in your project (dev-only).
Once installed, launch the REPL via composer repl (no extra setup required).
The REPL automatically loads your project’s vendor/autoload.php, giving immediate access to all installed packages and your own classes.
First use case: Instantly test how your project’s dependency (e.g., monolog/monolog) logs a message or how a custom utility class behaves.

Implementation Patterns

API Exploration: Use it to inspect method signatures, default options, or edge-case behavior (e.g., new MyService()->handle(...)) without writing and running a .php script.
Debugging Complex Flows: Pause mid-development to inspect $this state or intermediate values in a service—just paste in a quick variable dump or condition check.
Dependency Isolation: Before adding a new package, fire up composer repl and test it against your current dependency tree to catch version conflicts early.
Prototyping Logic: sketch and validate business rules, transform data, or simulate API responses interactively—then copy-paste working code into your codebase.

Class Autoloading Delays: If you add a new class file manually (e.g., in src/) without running composer dump-autoload, the REPL won’t find it—run composer dump-autoload after changes.
REPL Compatibility: Uses php://stdin and readline/linenoise; if your CLI environment lacks readline support (e.g., some Windows setups), it falls back to a basic input loop. Consider php -a as a fallback if composer repl fails.
Extension Point: You can add custom initialization code by creating a composer-repl.php file in your project root. It gets included before the REPL starts—perfect for preloading mocks, constants, or helper functions.
Avoid Production: Never install or use ramsey/composer-repl in production—it’s purely a dev tool and may leak sensitive context via interactive execution.