Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.dougwise.org!nntpfeed.proxad.net!proxad.net!feeder1-2.proxad.net!usenet-fr.net!de-l.enfer-du-nord.net!feeder2.enfer-du-nord.net!talisker.lacave.net!lacave.net!not-for-mail From: Kevin Mahler Newsgroups: comp.lang.ruby Subject: Re: What do you do when you need to attach data to an object instance? Date: Sat, 16 Apr 2011 10:32:22 -0500 Organization: Service de news de lacave.net Lines: 27 Message-ID: <41c1bcee810455547ca7d7844c1113d2@ruby-forum.com> References: <6fce5b6386258c51794d0b55b63e1ed6@ruby-forum.com> NNTP-Posting-Host: bristol.highgroove.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Trace: talisker.lacave.net 1302968633 70421 65.111.164.187 (16 Apr 2011 15:43:53 GMT) X-Complaints-To: abuse@lacave.net NNTP-Posting-Date: Sat, 16 Apr 2011 15:43:53 +0000 (UTC) In-Reply-To: X-Received-From: This message has been automatically forwarded from the ruby-talk mailing list by a gateway at comp.lang.ruby. If it is SPAM, it did not originate at comp.lang.ruby. Please report the original sender, and not us. Thanks! For more details about this gateway, please visit: http://blog.grayproductions.net/categories/the_gateway X-Mail-Count: 381702 X-Ml-Name: ruby-talk X-Rubymirror: Yes X-Ruby-Talk: <41c1bcee810455547ca7d7844c1113d2@ruby-forum.com> Xref: x330-a1.tempe.blueboxinc.net comp.lang.ruby:3010 7stud -- wrote in post #993115: > Kevin Mahler wrote in post #992907: >> >> def extend_accessor(obj, name) >> obj.singleton_class.module_eval { attr_accessor name } >> obj >> end >> > > Hey, now. obj.singleton_class is a class, so how about using the > synonym class_eval(): > > obj.singleton_class.class_eval { attr_accessor name } A class is a module, but a module is not a class. Class.new.is_a? Module #=>true Module.new.is_a? Class #=>false Because module_eval and class_eval are aliases, class_eval can be called on a module, a situation which is at worst wrong and at best confusing. module_eval can never be wrong or confusing. Not a hard choice. -- Posted via http://www.ruby-forum.com/.