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26. Closures & Arrow Functions

Anonymous functions and scope capture.

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Closures are created with the function keyword and can capture outer variables explicitly via the `use` clause, by value or by reference (`use (&$var)`). Arrow functions (`fn($x) => $x * 2`) automatically capture outer variables by value.

Closures implement the Closure class and can be bound to a different object/scope using bindTo() or Closure::bind().

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Check your understanding

1. How does a traditional closure capture an outer variable by reference?
use ($var)use (&$var)capture($var)ref($var)
2. What is a key feature of arrow functions (fn)?
They require explicit use()They auto-capture outer scope by valueThey cannot return a valueThey are slower than closures

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