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. Link exchange is nothing else however it is simply placing the other person’s webpage link on your page at suitable place and other person will also do similar in support of you.

  6. Great weblog right here! Also your web site
    a lot up fast! What web host are you using? Can I get your affiliate link for your host?
    I wish my site loaded up as quickly as yours lol

  7. Hi there, I discovered your blog by the use of Google
    whilst searching for a comparable matter, your site got here
    up, it seems to be good. I have bookmarked it in my google bookmarks.

    Hello there, simply became alert to your blog through Google,
    and located that it’s really informative. I’m gonna watch out for
    brussels. I’ll appreciate if you continue this in future.
    Lots of other people can be benefited out of your
    writing. Cheers!