From: Robert Klemme <bob.news@...>
Date: 2005-11-19T19:22:23+09:00
Subject: Re: Symbol#inspect bug?

Eric Mahurin <eric.mahurin@gmail.com> wrote:
> On 11/18/05, Eric Hodel <drbrain@segment7.net> wrote:
>>
>> On Nov 18, 2005, at 4:09 PM, Dominik Bathon wrote:
>>
>>> On Sat, 19 Nov 2005 00:57:28 +0100, Eric Hodel
>>> <drbrain@segment7.net> wrote:
>>>
>>>> On Nov 18, 2005, at 3:22 PM, Dominik Bathon wrote:
>>>>
>>>>> Symbol#inspect should return a valid symbol literal, right?
>>>>
>>>> Not according to the RDoc:
>>>>
>>>> $ ri Object#inspect
>>>>       Returns a string containing a human-readable representation
>>>>       of _obj_. If not overridden, uses the +to_s+ method to
>>>> generate
>>>> the
>>>>       string.
>>>
>>> Yes, but:
>>>
>>> $ ri Symbol#inspect
>>>      Returns the representation of sym as a symbol literal.
>>
>> I consider Object#inspect to set the intent of all the #inspect
>> methods, but this may be an oversight.
>
> For many of the other core classes (and definitely all other immediate
> classes), #inspect returns a representation that is eval'able to get
> back an equivalent (or the same) object.  When possible, I think that
> is what #inspect should do.  I think it is a bug that Symbol#inspect
> almost does it, but not quite (quotes some cases but not others).

Although I'd agree that Symbol#inspect can be improved and should be 
changend (as it's an easy fix) I have a different opinion about the usage of 
inspect in general: even inspect methods of core classes fail to return 
something that is proper ruby code.

$ ruby -e 'p Object.new'
#<Object:0x100f6b28>
$ ruby -e 'a=[1];a<<a;p a'
[1, [...]]

> I found this problem when doing code generation.  For immediate
> objects, I embedded the value in the code directly by using #inspect.
> I had to put in a hack for Symbol because of the problem discussed.

IMHO relying on #inspect for code generation is inappropriate.  As the rdoc 
of Object#inspect indicates it's meant to yield a human readable 
representation.  If you want to generate code you should use another 
mechanism.  For example, you can define a separate method (even if it calls 
#inspect as default implementation).  Or you use YAML / Marshal for complex 
data structures.

Kind regards

    robert