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. Les joueurs nouvellement inscrits reçoivent un bonus d’inscription au casino Betify pouvant aller
    jusqu’à 100 tours gratuits.

  2. Nice post. I was checking constantly this blog and I am impressed!

    Extremely useful information particularly
    the last part :) I care for such info a
    lot. I was looking for this certain information for a very long time.
    Thank you and best of luck.