Anonymous Functions in PHP 5.3 Matthew Weier O’Phinney 26 April 2011 But first, some vocabulary Lambdas • From “lambda calculus” 26 April 2011 Anonymous Functions in PHP 5.3 3 Lambdas • From “lambda calculus” • Names of functions are merely a “convenience”, and hence all functions are considered anonymous 26 April 2011 Anonymous Functions in PHP 5.3 3 Lambdas • From “lambda calculus” • Names of functions are merely a “convenience”, and hence all functions are considered anonymous • Unless you’re using a true functional programming language with first-class functions, most likely you’re simply using anonymous functions, or lambda expressions. 26 April 2011 Anonymous Functions in PHP 5.3 3 Closures • A function which includes a referencing environment 26 April 2011 Anonymous Functions in PHP 5.3 4 Closures • A function which includes a referencing environment • Each function has its own scope • Allows hiding state 26 April 2011 Anonymous Functions in PHP 5.3 4 Closures • A function which includes a referencing environment • Each function has its own scope • Allows hiding state • Differentiating factor is that closures allow binding references that exist at the time of creation, to use when called. 26 April 2011 Anonymous Functions in PHP 5.3 4 Anonymous Functions • Any function defined and/or called without being bound to an identifier. • You can assign the function to a variable, but you’re not giving it its own name. 26 April 2011 Anonymous Functions in PHP 5.3 5 PHP’s Offering