From: Phrogz <phrogz@...>
Date: 2007-09-19T03:50:05+09:00
Subject: Re: capturing access to array elements

On Sep 18, 11:10 am, mortee <mortee.li...@kavemalna.hu> wrote:
> So which methods in Array do I have to override, if I want to make sure
> I can capture any attempt to access an array element? In other words,
> which are the Array methods which don't rely on other ones to access
> elements?

Unfortunately, there isn't a single method that accesses the value at
a particular index. For example, see the following code. Note that the
#[] method isn't called by the other methods, including each. (Note
also that the following is not an exhaustive list, but does give you a
starting point for experimentally determining which method might call
others.)

a = %w| a b c |

def a.[]( *args, &blk  )
  p '[]'
  super *args, &blk
end

def a.each( *args, &blk )
  p 'each'
  super *args, &blk
end

def a.select( *args, &blk )
  p 'select'
  super *args, &blk
end

def a.delete( *args, &blk )
  p 'delete'
  super *args, &blk
end

def a.fetch( *args, &blk )
  p 'fetch'
  super *args, &blk
end

puts "Using []:"
a[ 0 ]

puts "-"*40

puts "Using each:"
a.each{ |x| }

puts "-"*40

puts "Using select:"
a.select{ |x| }

puts "-"*40

puts "Using delete:"
a.delete 'b'

puts "-"*40

puts "Using fetch:"
a.fetch 1