From: Allen Lee <allenlooplee@...>
Date: 2010-01-22T21:25:05+09:00
Subject: Re: Ruby equivalent of C# "using keword" and IDispose

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1) I also considered

def using(res, close = :close)

over

def using(res, options = { release_with: :close })

however, I think

using(Res.new, release_with: "close")

would be nicer than

using(Res.new, "close")

so finally I chose what it is right now :)

2) The solution you provided as follows is definitely more robust due to
respond_to? may not work as expected in the situation you mentioned and
thanks!

res.send(options[:release_with]) rescue nil

allen

On Fri, Jan 22, 2010 at 5:32 PM, Robert Klemme
<shortcutter@googlemail.com>wrote:

> 2010/1/22 Allen Lee <allenlooplee@gmail.com>:
> > I finally came up with this toy:
>
> This looks interesting.  Although I have to say that the functionality
> should be rather built into the classes at hand (like e.g. File has)
> IMHO.
>
> > def using(res, options = { release_with: :close })
>
> Since you have a single option only you can as well do
>
> def using(res, close = :close)
>
> >  yield res
> > ensure
> >  if res.respond_to?(options[:release_with])
> >    res.send(options[:release_with])
> >  end
>
> I'd rather do
>
>  res.send(options[:release_with]) rescue nil
>
> Because the idea of respond_to? and what the class really understands
> may differ.
>
> irb(main):001:0> class X
> irb(main):002:1> def method_missing(s,*a,&b)
> irb(main):003:2>   "I can #{s}!"
> irb(main):004:2> end
> irb(main):005:1> end
> => nil
> irb(main):006:0> o = X.new
> => #<X:0x101596fc>
> irb(main):007:0> o.respond_to? :dance
> => false
> irb(main):008:0> o.dance
> => "I can dance!"
> irb(main):009:0> o.dance!
> => "I can dance!!"
> irb(main):010:0>
>
> > end
> >
> > Note that you need to go back to :release_with => "close" if you are
> > targeting version before 1.9.
>
> This is not necessary if you just use a single additional parameter (see
> above).
>
> Kind regards
>
> robert
>
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>
>

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