From: Charles Oliver Nutter <headius@...>
Date: 2011-01-12T04:59:46+09:00
Subject: [ruby-core:34383] Re: [Ruby 1.9-Feature#4264][Open] General type coercion protocol for Ruby

On Tue, Jan 11, 2011 at 12:23 PM, Jim Weirich <jim.weirich@gmail.com> wrote:
>
> On Jan 11, 2011, at 1:17 PM, James Edward Gray II wrote:
>
>> I understood it as to_a/to_s are for conversions. ��They basically mean
>> change this object into an Array or a Sring, however it makes sense to do
>> that for the current object.
>>
>> In contrast, to_ary/to_str are for objects that essentially are enhanced
>> versions of Array or String. ��They mean, it's OK to pretend this object is
>> an Array or a String.
>>
>> Perhaps I'm wrong though.
>
>
> That's my understanding as well.

The logic is inconsistently applied in Ruby right now. Sometimes
to_str means treat me as a string without any additional calls,
sometimes it's called blindly, sometimes it's checked and called...and
sometimes to_s is used instead. However to_str and to_ary are used
much more heavily during call protocols (usually by the receiver) than
to_a and to_s. The latter two are more heavily used for user-driven
conversions.

Whether what's described above is correct or not (or desirable), I
think the current real-world uses of to_ary/to_str fit my description
better.

The lack of a formal statement on coercion/conversion protocols is
probably responsible for this confusion in the first place.

- Charlie