From: Simon Strandgaard <neoneye@...>
Date: 2004-02-20T20:20:37+09:00
Subject: Re: proposal: let kind_of take more arguments

On Thu, 19 Feb 2004 16:14:13 +0100, Robert Klemme wrote:
> "Simon Strandgaard" <neoneye@adslhome.dk> schrieb im Newsbeitrag
>> On Thu, 19 Feb 2004 15:43:05 +0100, Robert Klemme wrote:
>> >
>> > Why don't you just do
>> >
>> > def push(choice)
>> >   case choice
>> >     when Zero, One
>> >       @choices << choice
>> >     else
>> >       raise ArgumentError, "got #{choice.class}"
>> >   end
>> > end
>>
>> a switch statement.. easier to read.
>> However I like to do bailout as soon as possible,
>> raising ArgumentError this late may make confusion.
> 
> What do you mean by "late"?  Do you mean that the line with "raise" stands
> below the actual operation.  Didn't think of that, but yes, it might be
> confusing.  OTOH, if you can read "case" then it's not so difficult, is
> it?

It isn't clear at first sight when the method bailouts, and if
the switch statement spans over many lines, then its not visible at all
that its capable of raising exceptions.

Kind_of? similar to bouncer pattern, see
http://www.rubygarden.org/ruby?BouncerPattern

 
>>
>> Confusion :-)
> 
> http://lyricsheaven.topcities.com/survey_d_k_bestanden/ELO.htm#confusion

:-)

 
>> > def Object#kind_of_any?( *classes )
>>
>> Yes thought of this.. which maked me propose this idea.
> 
> I'm wondering though whether it's worth the effort.  When using duck
> typing, you don't need kind_of? anyway.
> 
> Btw, I had another idea:
> 
> PUSH_ALLOWED = {Zero, One}
> 
> def push(choice)
>   raise ArgumentError, "got #{choice.class}" unless
> PUSH_ALLOWED[choice.class]
>   @choices << choice
> end

Good idea, but gives a complex impression at first sight.

 
> Of course there is a subtle difference since this does not take sub
> classes into consideration.  But other than that, it should be faster -
> especially if you have more classes that shoule be checked.

Im in the make it work phase.

There is 3 phases: 
1)  make it work
2)  make it right
3)  make it fast   ;-)

--
Simon Strandgaard