I find it a bit strange that puts treats array objects differently
than all other objects. Strings are simply written to stdout, objects
other than arrays are converted to strings by calling to_s and then written,
but arrays are handled via the recursive algorithm shown above. The effect
is to 'flatten' recursive array structures and then write the to_s version of
each object on a separate line.
My expectation was that Array#to_s would be called for array arguments but it
turns out that Array#to_s doesn't generate the same results as the recursive
algorithm that Dave shows above.
Even more puzzling is that IO#print doesn't treat array objects specially, and
simply calls Array#to_s.
Prior to 1.8, Array#to_s simply concatenated the results of calling #to_s on each
element of the array. In 1.9 Array#to_s generates an inspect-like string for the
array:
ruby 1.8.5: [1,2].to_s => 12
ruby 1.9: [1,2].to_s => [1, 2]
ruby 1.8.5: print [1,2] => 12
ruby 1.9: print [1,2] => [1, 2]
ruby 1.8.5: puts [1,2] => 1\n2\n
ruby 1.9: puts [1,2] => 1\n\2\n
I guess that the puts behavior is in some sense a shortcut for a common need
(instead of writing puts *a.flatten), but it seems anomalous to me.
If you use nested arrays to model a tree structure then Array#to_s is a very nice way to
do a pre-order traversal of the structure generating a textual representation of the tree.
This works just fine in 1.8, but in 1.9 you get burned. I suspect that there might be quite
a bit of code that expects the 1.8 behavior for Array#to_s than the 1.9 behavior.
Maybe I'm missing something but I think to get the 1.8 Array#to_s behavior in 1.9 you would
have to write something like:
a.flatten.inject("") { |s,i| s << i.to_s }
Gary Wright
···
On Nov 30, 2006, at 2:39 PM, dblack@wobblini.net wrote:
And, I now realize, if someone posted what I posted and I were
responding to it, I would point out that:
array.each {|e| puts e }
is the same as:
puts array
Something I've described in the past as a nuby rite of passage, I
believe... 