CoffeeScript lazy singleton class instance function

Posted on by

Explanation

“@instance:” allows us to attach an object/value to the Foo class instead of Foo’s prototype. Recall that “@” in CoffeeScript refers to JavaScript’s “this”.

After “@instance:” there is a function that is immediately executed. This function returns a function, closed around a variable called instance. Both these functions have their context (their “this”) bound to the Foo object using CoffeeScript’s wonderful “define and bind” operator “=>” as opposed to the normal function definition operator “->”.

When called, the function that “@instance” ends up referring to simply checks to see if the “instance” variable is empty and if so, assigns a new instance of Foo to it. Newing up a Foo is done using the “@” symbol since the function’s “this” refers to the Foo object. It then returns the instance.

Output

The CoffeeScript above compiles down to this:

23,235 thoughts on “CoffeeScript lazy singleton class instance function”

  2. 부산출장마사지는 ‘부산출장안마’ 또는 ‘부산홈타이’
    등으로도 불리며, 고객이 계신 곳으로 전문 테라피스트가
    직접 찾아가 마사지를 제공하는 서비스입니다.