CODEWITHSUNDEEP
coffeescript
Kirk Strobeck
Kirk Strobeck

Reputation: 18589

How do I make an Array of Arrays?

I'm trying to do something like this with coffescript, but it isn't working ..

locations =
  [59.32522, 18.07002]
  [59.327383, 18.06747]

Upvotes: 3

Views: 93

Answers (2)

Mark Essel
Mark Essel

Reputation: 4646

I realize you found a solution for your own question, and this is not exactly the precise answer you're looking for Kirk. But in Ruby there's an arbitrary hash of hashes object that I'm fond of (note they are more memory intensive than a fixed dimensional array).

From: http://www.ruby-forum.com/topic/130324

Author: Sebastian Hungerecker

blk = lambda {|h,k| h[k] = Hash.new(&blk)}
x = Hash.new(&blk)
x[:la][:li][:lu][:chunky][:bacon][:foo] = "bar"

What's interesting about this structure is that you can use it create any sort of nested hash you need on the fly (kinda like making subdirectories as you go with mkdir -p ). It share's some qualities with JSON objects.

Let's see what a similar object would look like in CoffeeScript

x = 
  la:  
    li:  
      lu:  
        chunky:  
          bacon:  
            foo: 'bar' 

alert x['la']['li']['lu']['chunky']['bacon']['foo']


y = { la: { li: { lu: { chunky: { bacon: { foo:'bary' } } } } } }  

alert y['la']['li']['lu']['chunky']['bacon']['foo']

I haven't been able to come up with a cleaner create as you go interface than pure JSON object creation since bracket operators can't be overloaded in Javascript

Ok, I came up with a slight abbreviation to the JSON syntax, but it's not as nice as the Ruby nestedHash.

Block = (obj,rest...) ->
  console.log 'obj',obj
  console.log 'rest',rest
  obj = {} if (typeof obj is "undefined") 
  if rest.length >= 2
    key = rest[0]
    obj[key] = Block(obj[key],rest[1...]...)
    obj
  else if rest.length is 1
    obj = rest[0]

z = new Block(z,'la','li','lu','chunky','bacon','foo','barz')
console.log z['la']['li']['lu']['chunky']['bacon']['foo']
# extend the object
z = new Block(z,'la','li','lu','chunky','bacon','fooz','ball')
console.log JSON.stringify(z)

# add a node to an internal hash
a = z['la']['li']['lu']
a = new Block(a,'chunky','bacon','another','node')
console.log 'a is',JSON.stringify(a)

# the node now exists on the parent as well
console.log 'z is',JSON.stringify(z)

Upvotes: 1

Kirk Strobeck
Kirk Strobeck

Reputation: 18589

Oh, I figured it out ..

locations = [
  [59.32522, 18.07002]
  [59.327383, 18.06747]
]

Upvotes: 2

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