From: Brian Candler <b.candler@...>
Date: 2011-04-19T00:53:08+09:00
Subject: Re: To Yield or Not to Yield: An Inferable Question

Michael Edgar wrote in post #993395:
>> 1. In my experience, very little real-world Ruby code uses
>> 'block_given?'. If it needs to yield, it just yields. I'd consider this
>> to be a case of duck-typing.
>
> This seems to suggest Rubyists rarely write methods that take blocks
> optionally. Of this, I am highly skeptical.

Ah, by "optionally" I think you mean "does one thing when a block is 
given, but something else when a block is not given". Now I think some 
more, there is a fairly common case:

class MyFile
  def self.open(*args)
    file = open_it(*args)
    if block_given?
      begin
        yield file
      ensure
        file.close
      end
    else
      return file
    end
  end
end

Code analysis can tell you that it's OK to call the method either with 
or without a block (at least assuming no pathological use cases, like 
redefining 'block_given?')

Regards,

Brian.

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