From: Christoph Rippel <chr@...>
Date: 2000-11-22T22:45:21+09:00
Subject: [ruby-talk:6517] Re: Question about the behavior of write attributes in blocks

Thank you very much for your insightful (and speedy) response.  Is it at all
possible to write an iterator, which allows assignments inside a block?  I
have a vague understanding that the main obstacle is the fact that ``x=y''
does not involve a method invocation.

I played around with the build in iterator for the Array class and came up
with a ``program-let''
**************************************
def surprise(y)
sep="---"
j="A"
for i in y do
   print i+sep
   i  << j        # this is a destructive method - similar to replace
   print i+sep
   i += j
   print i+sep
   i.replace "f"
   print i

   j.succ!
   puts
end
end


dyn =  Array.new(3,"x")
sta = ["x","x","x"]

surprise dyn
puts
surprise sta

**************************************
with a rather surprising  output ...
>>x---xA---xAA---f
>>xA---xAB---xABB---f
>>xAB---xABC---xABCC---f
>>
>>x---xA---xAA---f
>>x---xB---xBB---f
>>x---xC---xCC---f

I am not sure if this is a bug but it certainly violates the ruby principle
of ``least surprise''.   Any thoughts?

Thanks,
        Christoph