From: Kent Dahl <kentda@...>
Date: 2002-10-12T01:57:17+09:00
Subject: Re: Different Behavior of Class Variables w.r.t ||=

nobu.nokada@softhome.net wrote:
> At Sat, 12 Oct 2002 00:57:04 +0900,
> Kent Dahl wrote:
> > The inheritance hierarchy level where the class variable is first
> > defined decides where it is visible. This is not a problem with local
> > variables nor instance variables. Although it is alot more verbose,
> > using the "@@a = 1 unless defined? @@a" trick gives you the same
> > functionality, but is easier to spot while reading, if it causes a bug.
> 
> Oops, 1.7 behavior has changed.  Bad idea?
> # [ruby-talk:50421] & [ruby-dev:18278]

I am not too sure which way it has been made consistent. Does ||= work
on all variables similarly now? It looks like it, from what I can gather
from the patch source... *cvs update, compile* ... yup, ||= works on all
now.

If all types of variables now work with ||=, that isn't necessarily a
bad idea, but writing Ruby code that sets a class variable using ||=
somewhere which might cause it to be defined at the wrong hierarchy
level might be a bad idea. As for what Ruby should do, it really is a
weighing of "shooting foot" versus "ease of toe nail cutting" that it
appears Matz already has made a call on. :-)

I will probably succumb to using the terser ||= with class variables
myself over time, but I have already learned the pitfall. Don't know
about nubies, as YMMV.

-- 
(\[ Kent Dahl ]/)_    _~_    __[ http://www.stud.ntnu.no/~kentda/ ]___/~
 ))\_student_/((  \__d L b__/  NTNU - graduate engineering - 5. year  )
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