.include?/.within? and English-thinking brains

ruby-talk
1

In English, it's clearer to ask, "Is Maggie one of the guests?" -- rather than the awkward, "Does the guests include Maggie?"

So why in Ruby, do we write, "list.include? scalar" -- when we often mean, "scalar.within? list" ?!

The solution:

   module Comparable
     def within?(list)
       list.include? self
     end
   end

···

#
   # Examples:
   #

   1.within? [1,2,3]
   # => true

   1.within? [2,3]
   # => false

   "arr".within? "arr, matey"
   # => true

   "arr".within? "monkey patch"
   # => false

   1.within?( 1 => "value" )
   # => true

   1.within?( 2 => "value" )
   # => false

   1.within? 1..3
   # => true

   1.within? 2..3
   # => false

Try it for a morning, your brain will feel better.

2

HI --

In English, it's clearer to ask, "Is Maggie one of the guests?" -- rather than the awkward, "Does the guests include Maggie?"

Well, you're stacking the deck a bit to make it sound awkward ("Does
the guests") :slight_smile: Anyway, we have both; it all depends what you're
trying to say.

So why in Ruby, do we write, "list.include? scalar" -- when we often mean, "scalar.within? list" ?!

Because Ruby isn't English; we use both in English anyway; and Ruby
doesn't have #within? :slight_smile:

The solution:

module Comparable
  def within?(list)
    list.include? self
  end
end

There's been discussion of this in the past; have a look for #in?
proposed by Hal a while back.

David

···

On Tue, 26 Jun 2007, Michael Judge wrote:

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