CODEWITHSUNDEEP
hashcoffeescript
Erik Nomitch
Erik Nomitch

Reputation: 1665

Defining a CoffeeScript Hash Object using its own values in one motion

Since I can't use the hash's values until they're defined, I was doing this:

@Foo =
  Protocol: "http"
  Domain:   "foo.com"

# Annoying...
@Foo.Url = "#{Foo.Protocol}://#{Foo.Domain}"

Ideally, I'd be doing something like this (one motion):

# Doesn't work obviously...

@Foo =
  Protocol: "http"
  Domain:   "foo.com"
  Url:      "#{Foo.Protocol}://#{Foo.Domain}"

Is there any way to do this?

The best methods I can come up with are:

Using Closures

@Foo = do =>
  protocol = "http"
  domain   = "foo.com"
  url      = "#{protocol}://#{domain}"

  protocol: protocol
  domain:   domain
  url:      url

Using $.extend

$.extend @Foo =
  protocol: "http"
  domain:   "foo.com"
,
  url: "#{Foo.protocol}://#{Foo.domain}"

Thanks,

Erik

Upvotes: 0

Views: 48

Answers (1)

Daniel Ma
Daniel Ma

Reputation: 646

One option is to use functions instead of properties.

@Foo =
  Protocol: -> "http"
  Domain:   -> "foo.com"
  Url:      -> "#{this.Protocol()}://#{this.Domain()}"

@Foo.Url() == "http://foo.com"

Or, if you wanted to use regular javascript, you could use a getter

Foo = {
  Protocol: 'http',
  Domain:   'foo.com',
  get Url() {
    return this.Protocol + '://' + this.Domain;
  }
}

Foo.Url == 'http://foo.com'

Foo.Protocol = 'https'

Foo.Url == 'https://foo.com'

Upvotes: 1

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