From: Robert Dober <robert.dober@...>
Date: 2007-07-20T21:04:00+09:00
Subject: Re: block_given? problem

On 7/20/07, westlin9@gmail.com <westlin9@gmail.com> wrote:
> I can't figure out why the do...end block isn't detected by the
> "block_given?" function. The problem occurs when a method call with a
> block is used in a puts statement. See the code example below.
> Can some one explain this to me please? Is this a bug?
>
>
> class TheClass
>   def self.TheMethod()
>     if block_given?
>       puts "yes, block given"
>     else
>       puts "no block is given"
>     end
>     'return val'
>   end
> end
>
> # ok
> puts TheClass.TheMethod {|param| 123}
>
> # block not detected
> puts TheClass.TheMethod do |param|
>   123
> end
>
> # ok
> a = TheClass.TheMethod {|param| 123}
> puts a
>
> # ok
> a = TheClass.TheMethod do |param|
>   123
> end
> puts a
>
>
>
 puts( TheClass.TheMethod do nil end )

do...end and {} do not have the same precedence, thus, without the ()
you are doing this
puts( TheClass.TheMethod ) do nil end

HTH
Robert

-- 
I always knew that one day Smalltalk would replace Java.
I just didn't know it would be called Ruby
-- Kent Beck