Array#===

ruby-talk
1

It seems a bit of a waste for Array#=== to default to Object#=== - it'd
be far more useful, IMO, to have it call include?. Can anyone see a
drawback to this?

Here's a real-world use case from the FXIrb code:

  def onKeyPress(sender,sel,event)
    case event.code
    when Fox::KEY_Delete,Fox::KEY_KP_Delete,Fox::KEY_BackSpace
      if getCursorPos > @anchor
        super
      end

which a change to Array#=== would let me write as

  config[:delete_keys] =
    [Fox::KEY_Delete,Fox::KEY_KP_Delete,Fox::KEY_BackSpace]
  .
  .
  .
    when config[:delete_keys]
      __etc__

martin

2

I've wondered about this too. It seems that the === method loosely
translates to a membership test, so it would make sense if it tested
membership with arrays, as well as ranges and classes and regexps. I
can't see any drawbacks, though. (though that doesn't mean there
aren't any)

cheers,
Mark

···

On Sun, 20 Feb 2005 07:04:44 +0900, Martin DeMello <martindemello@yahoo.com> wrote:

It seems a bit of a waste for Array#=== to default to Object#=== - it'd
be far more useful, IMO, to have it call include?. Can anyone see a
drawback to this?

3

Martin DeMello wrote:

It seems a bit of a waste for Array#=== to default to Object#=== - it'd
be far more useful, IMO, to have it call include?. Can anyone see a
drawback to this?

Here's a real-world use case from the FXIrb code:

  def onKeyPress(sender,sel,event)
    case event.code
    when Fox::KEY_Delete,Fox::KEY_KP_Delete,Fox::KEY_BackSpace
      if getCursorPos > @anchor
        super
      end

which a change to Array#=== would let me write as

  config[:delete_keys] =
    [Fox::KEY_Delete,Fox::KEY_KP_Delete,Fox::KEY_BackSpace]
  .
    when config[:delete_keys]
      __etc__

martin

How about using the splat idiom?

a = [1,2,3]
case 3
when *a; p a
end

4

Martin DeMello wrote:

It seems a bit of a waste for Array#=== to default to Object#=== - it'd
be far more useful, IMO, to have it call include?. Can anyone see a
drawback to this?

We'd lose this, FWIW:

points = [
   [1,2],
   [3,4],
   [0,0]
]

points.each do |point|
   case point
   when [0,0]
     puts "origin!"
   end
end

To be a bit philosophical, I'd say that Arrays, unlike Regexps, do not exist primarily to match, and so #=== should be Object#===.

5

Very neat - didn't think of that.

martin

···

Joel VanderWerf <vjoel@path.berkeley.edu> wrote:

How about using the splat idiom?

a = [1,2,3]
case 3
when *a; p a
end