Domain Specific Languages

Chapter 37. Closure

A block of code that can be represented as an object (or first-class data structure) and placed seamlessly into the flow of code by allowing it to reference its lexical scope.

var threshold = ComputeThreshold();var heavyTravellers = employeeList.FindAll(e => e.MilesOfCommute > threshold);

Also known as: lambda, block, or anonymous function

You have a collection of objects and want to filter them in various ways. Writing a method for each filter leads to duplication in the setup and processing of the filter.

By using a Closure, you can factor the setup and processing of the filter and pass in an arbitrary block of code for each filter condition.

37.1 How It Works

Closures are a language feature that, despite being around ...