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”

  1. Heya terrific blog! Does running a blog such as this require a massive amount work?

    I’ve virtually no knowledge of coding however I had been hoping to start my own blog in the near future.
    Anyway, should you have any recommendations or tips for new blog owners please share.
    I know this is off subject however I simply had to
    ask. Thank you!

  2. https://s3.fr-par.scw.cloud/pelletofentest/untapped-opportunities-in-the-pellet-stove-testing-industry.html

    Just want to say your article is as surprising. The clearness in your post is simply spectacular and i can assume
    you are an expert on this subject. Well with your permission let me to grab your feed to keep updated with forthcoming post.

    Thanks a million and please continue the enjoyable work.