See this article on alistapart.com. (Ed: The article has been updated since originally linked) self is being used to maintain a reference to the original this even as the context is changing. It’s a technique often used in event handlers (especially in closures). Edit: Note that using self is now discouraged as window.self exists and … Read more
Compare this, without using nonlocal: x = 0 def outer(): x = 1 def inner(): x = 2 print(“inner:”, x) inner() print(“outer:”, x) outer() print(“global:”, x) # inner: 2 # outer: 1 # global: 0 To this, using nonlocal, where inner()‘s x is now also outer()‘s x: x = 0 def outer(): x = 1 … Read more
A simpler answer. function ($quantity) use ($tax, &$total) { .. }; The closure is a function assigned to a variable, so you can pass it around A closure is a separate namespace, normally, you can not access variables defined outside of this namespace. There comes the use keyword: use allows you to access (use) the … Read more
It’s all about variable scoping. Variables declared in the self executing function are, by default, only available to code within the self executing function. This allows code to be written without concern of how variables are named in other blocks of JavaScript code. For example, as mentioned in a comment by Alexander: (function() { var … Read more
Editor’s Note: All functions in JavaScript are closures as explained in this post. However we are only interested in identifying a subset of these functions which are interesting from a theoretical point of view. Henceforth any reference to the word closure will refer to this subset of functions unless otherwise stated. A simple explanation for … Read more
If you come from a class-based, statically typed object-oriented language (like Java, C++ or C#) I assume that you are trying to create a variable or method associated to a “type” but not to an instance. An example using a “classical” approach, with constructor functions maybe could help you to catch the concepts of basic … Read more
A lambda is just an anonymous function – a function defined with no name. In some languages, such as Scheme, they are equivalent to named functions. In fact, the function definition is re-written as binding a lambda to a variable internally. In other languages, like Python, there are some (rather needless) distinctions between them, but … Read more
Are you talking about lambda expressions? Like lambda x: x**2 + 2*x – 5 Those things are actually quite useful. Python supports a style of programming called functional programming where you can pass functions to other functions to do stuff. Example: mult3 = filter(lambda x: x % 3 == 0, [1, 2, 3, 4, 5, … Read more
Well, the problem is that the variable i, within each of your anonymous functions, is bound to the same variable outside of the function. ES6 solution: let ECMAScript 6 (ES6) introduces new let and const keywords that are scoped differently than var-based variables. For example, in a loop with a let-based index, each iteration through … Read more