From: "NARUSE, Yui" <naruse@...>
Date: 2009-11-21T16:59:10+09:00
Subject: [ruby-core:26857] Re: Internals: #to_s .vs. #to_str?

% irb19
irb(main):001:0> class Foo;def to_s;"to_s";end;def to_str;"to_str";end;end
=> nil
irb(main):002:0> "#{Foo.new}"
=> "to_s"

This seems because all object shouold be embeded in "#{obj}".

Kurt Stephens wrote:
> Does "123#{xyz}456" use xyz.to_s or xyz.to_str?
> 
> NARUSE, Yui wrote:
>> Kurt Stephens wrote:
>>> Is there a description of the semantic differences between #to_s and
>>> #to_str?  Are there any particular constraints on the results of these
>>> methods?  Is it considered "legal" to return frozen Strings in some
>>> cases for either of the two?   Is one used internal for implicit casts?
>>>
>>> I have some ideas that may reduce GC work and improve large String
>>> concatenation.
>>>
>>> I do remember a discussion about the differences between #to_a and
>>> #to_ary, but I don't quite remember why they are semantically different.
>>
>> to_int, to_str, to_ary, to_hash are fot implicit conversion.
>> path.to_str is called in path of following code, if path is not String:
>>   open(path){|f| ... }
>>
>> to_i, to_s, to_a are explicit conversion.
>>
>> David Flanagan's Programing Language Ruby describes
>> those type conversion of Ruby at 3.8.7.

-- 
NARUSE, Yui  <naruse@airemix.jp>