Advanced PHP · Lesson 6 of 10

Autoloading

Load namespaced classes automatically using Composer autoload rules.

Lesson

Autoloading removes manual require statements for every class. Composer's PSR-4 mapping connects a namespace prefix to a source directory; class names and file names must follow the expected casing, especially on case-sensitive systems. Regenerate the autoloader after changing mappings. Keep application classes under the mapped namespace and directory. Further guidance Make failure behavior explicit at system boundaries: validate decoded data, handle expected exceptions, and log diagnostics without exposing them to visitors. Keep dependencies locked and current, use a consistent namespace/autoloading scheme, and test error paths as well as successful responses. Practice task: Create a fresh example for Autoloading. Predict the result before running it, then change one input and explain why the result changes. Test a normal case and one boundary or invalid case where it applies. Compare your output with the example and note one rule you would use in a real project.

Code examples

Autoloading

JSON

{
  "autoload": {
    "psr-4": {
      "App\\": "app/"
    }
  }
}

Expected output

Composer resolves App\Support\Example from app/Support/Example.php

Key points

Load namespaced classes automatically using Composer autoload rules.
Handle expected errors explicitly without exposing diagnostics.
Keep dependency and runtime configuration reproducible.

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