From: matz@... (Yukihiro Matsumoto)
Date: 2001-12-11T02:59:54+09:00
Subject: [ruby-talk:28113] Re: How does puts decide how to print a given object?

Hi,

In message "[ruby-talk:28087] Re: How does puts decide how to print a given object?"
    on 01/12/10, David Alan Black <dblack@candle.superlink.net> writes:

|I can understand that for Array... but the thing that I found un-POLS-like
|is:
|
|  class Thing < Array
|    def to_s
|    # ...
|    end
|  end
|
|and then Thing objects still get puts'd according to the rules of how
|Array is handled.
|
|In other words, not only is Array a special case, but overriding the
|puts behavior/results for Array subclasses is a special case.  The
|former makes sense to me; the latter doesn't.
|
|Is this negotiable? :-)

I have experimented about this issue for the last few weeks on the
latest CVS.  I changed puts to stop array handling, and call to_s for
every object.

But..

  (1) it breaks some code.

  (2) to recover (1), I changed Array#to_s behavior, but things went
      worse.  notice recent Rubicon failures?

  (3) unlike other objects, arrays are sometimes very big.  imagine
      the code like 'puts File.readlines("bigfile")'.  calling to_s
      inside wastes huge memory region.

So my conclusion is Array should be treated specially by puts.
It is false assumption that puts should call to_s.

Hooking some Array method (like in [ruby-talk:28091]) is worth
consider though.

							matz.