CoffeeScript lazy singleton class instance function

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

  1. Greetings! I’ve been reading your weblog for a while now and finally got the bravery to go ahead
    and give you a shout out from Humble Tx! Just wanted to tell you keep up the good job!

  2. I know this web page provides quality depending articles and extra
    material, is there any other web site which offers such things in quality?

  3. I’m pretty pleased to uncover this page. I wanted to thank you for your time for this particularly
    fantastic read!! I definitely appreciated every little bit of it and i also have
    you saved to fav to check out new stuff on your site.