From: Aredridel <aredridel@...>
Date: 2004-04-03T08:33:42+09:00
Subject: Re: deciding between ruby and python

>     Jim> I think Ville means that making join a method on a list means
>     Jim> that lists must now know about strings.  Unfortunately,
>     Jim> removing join as a list method still leaves lists
>     Jim> knowledgeable about string for every object implements a to_s
>     Jim> method.
> 
> I mostly meant that the sequence has a special case for the list of
> strings. We have __str__ in Python too, but ''.join doesn't call it:
> 
> >>> '-'.join([12,13])
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> TypeError: sequence item 0: expected string, int found
> 
> Calling to_s() seems kinda brutal from the Python POV. Perhaps this is
> one of the areas where Ruby chooses the follow the Perl school of
> Convenience.

And it certainly is convenient:

the following is hypothetical, but useful:

class Socket
  def to_s
    "src: #{source}, dest: #{dest}"
  end
end

Then with an array of Sockets, you can do:

	[......].join("\n")

src: 10.10.0.0 dest: 10.10.0.1
src: 10.10.0.0 dest: 10.10.0.2

Useful?

The tradition of duck-typing and various kinds of hammer to coerce
objects into acting like the appropriate types is an appealing part of
Ruby.

Ari