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12. Tools & Composer

What is Composer?​

Junior

Answer: A dependency manager for PHP that allows you to declare the libraries your project depends on and manages (install/update) them for you.

What is the difference between composer.json and composer.lock?​

Junior

Answer:

  • composer.json: Lists the required dependencies and their version constraints.
  • composer.lock: Stores the exact versions of the packages that were installed.

What is the difference between composer install and composer update?​

Junior

Answer:

  • composer install: Checks for composer.lock file. If it exists, it installs the exact versions listed there. If not, it reads composer.json, installs the latest compatible versions, and creates the lock file.
  • composer update: Ignores composer.lock and tries to update all packages to the latest versions allowed by the constraints in composer.json, then updates the lock file.

What is Autoloading and how does Composer handle it?​

Middle

Answer: Autoloading automatically loads class files when they are needed. Composer uses PSR-4 (and others) to map namespaces to directories.