Closure

There are 6 posts tagged Closure.

JavaScript. The Core: 2nd Edition

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Read this article in: Russian, German.

This is the second edition of the JavaScript. The Core overview lecture, devoted to ECMAScript programming language and core components of its runtime system.

Note: see also Essentials of Interpretation course, where we build a programming language similar to JavaScript, from scratch.

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ECMA-262-5 in detail. Chapter 3.2. Lexical environments: ECMAScript implementation.

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  1. Introduction
  2. Definitions
  3. Environment record types
    1. Declarative environment record
      1. Eval and inner functions may break optimizations
    2. Object environment record
  4. Structure of execution context
    1. This binding
    2. Variable environment
    3. Lexical environment
  5. Identifier resolution
  6. Conclusion
  7. Additional literature

Introduction

In this chapter we continue our consideration of lexical environments. In the previous sub chapter 3.1 we clarified the general theory related with the topic. In particular we have learned that the concept of environments is closely related with concepts of static scope and closures. Continue reading →

ECMA-262-5 in detail. Chapter 3.1. Lexical environments: Common Theory.

  1. Introduction
  2. Common Theory
    1. Scope
      1. Static (lexical) scope
      2. Dynamic scope
        1. With and eval as dynamic scope features in ECMAScript
    2. Name binding
      1. Rebinding
      2. Mutation
    3. Environment
      1. Activation record model
      2. Environment frames model
        1. First-class functions
        2. Funargs and higher-order functions
        3. Free variable
        4. Environment definition
        5. Rules of function creation and application
        6. Closure
        7. Funarg problem
      3. Combined environment frame model
  3. Conclusion
  4. Additional literature

Introduction

In this chapter we’ll talk in detail about lexical environments — a mechanism used in some languages to manage the static scoping. In order to understand this concept completely, we’ll also discuss briefly the alternative — dynamic scoping (which though isn’t used directly in ECMAScript). We’ll see how environments help to manage lexically nested structures of a code and to provide complete support of closures. Continue reading →

ECMA-262-3 in detail. Chapter 6. Closures.

Read this article in: Russian, French.

  1. Introduction
  2. General theory
    1. Definitions
    2. Funarg problem
    3. Closure
  3. ECMAScript closures implementation
    1. One [[Scope]] value for “them all”
    2. Funarg and return
    3. Theory versions
  4. Practical usage of closures
  5. Conclusion
  6. Additional literature

Introduction

In this article we will talk about one of the most discussed topics related to JavaScript — about closures. The topic in fact is not new, and was discussed many times. However we will try to discuss and understand it more from a theoretical perspective, and also will look at how closures are implemented in ECMAScript.
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Тонкости ECMA-262-3. Часть 6. Замыкания.

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  1. Введение
  2. Общая теория
    1. Определения
    2. Фунарг-проблема
    3. Замыкание
  3. Реализация замыканий в ECMAScript
    1. Один [[Scope]] на “всех”
    2. Фунарг и return
    3. Версии теории
  4. Применение замыканий
  5. Заключение
  6. Дополнительная литература

Введение

В этой заметке мы поговорим об одной из наиболее обсуждаемых тем, связанных с JavaScript — о замыканиях. Тема, по сути, избита; существует немалое количество статей, посвящённых этой структуре (некоторые из них очень хорошие, например, статья R. Cornford-a, представленная в списке дополнительной литературы), однако мы постараемся разобрать её более с теоретической точки зрения, и посмотрим, как замыкания в ECMAScript устроены изнутри.
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