From: matz@... (Yukihiro Matsumoto)
Date: 2004-04-05T16:13:41+09:00
Subject: to_str (Re: deciding between ruby and python)

Hi,

In message "Re: deciding between ruby and python"
    on 04/04/05, Dave Benjamin <ramen@lackingtalent.com> writes:

|I'd really like to understand what you mean, here. In your first sentence,
|did you mean to say "I expect the object to be a duck *that* quacks like
|strings?" If so, what does it mean to quack like a string? If not, what were
|you really trying to say?

Suppose you understand "duck typing".

Defining "to_str" is a way to make an object to behave like string
_argument_.  Some C defined built in methods require String structure
inside.  This is against duck typing principle, but need to be so for
performance.  Those methods call "to_str" before processing string
arguments, as work around.  When you want to implement an object that
behave exactly like strings, you need to define "to_str" method that
returns string representation (i.e. one with String structure) along
with other methods in String class.

In summary, "to_str" should always be part of string method set (since
it's a performance hack).  Emphasizing "to_str" alone too much is not
encouraged.

							matz.