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. Halo 3: ODST 2009 first-person shooter recreation developed by Bungie.
    Published by Microsoft Game Studios. The fifth installment in the Halo franchise as a facet recreation,[1] it was released on the Xbox
    360 in September 2009. Players assume the roles of United Nations
    Space Command Marines, known as “Orbital Drop Shock Troopers” or ODSTs, during and after
    the events of Halo 2. In the sport’s campaign mode,
    players discover the ruined city of latest Mombasa
    to discover what occurred to their missing teammates within the midst of an alien invasion. In the
    “Firefight” multiplayer choice, gamers battle more and more troublesome waves of enemies to score factors and survive as long
    as possible; Halo 3′s multiplayer is contained on a separate disc packaged with ODST.

  5. Magnificent beat ! I would like to apprentice while you amend
    your site, how could i subscribe for a blog website?
    The account helped me a acceptable deal. I have been a little
    bit acquainted of this your broadcast offered brilliant clear concept

  8. obviously like your web site but you need to test the spelling
    on quite a few of your posts. Several of them are rife with
    spelling problems and I in finding it very troublesome to tell the truth on the
    other hand I will certainly come back again.