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Charles

2008-May-07 19:37 UTC

yields and blocks in Rails

The below code works just fine in Ruby but I get a LocalJumpError in
Rails stating "no block given". I thought I knew what a block was, but
given the results, I am not so sure. Could someone please offer an
explanation as to what is going on?

Thanks,
C.


class Array
  def comb(n = size)
    if size < n or n < 0
    elsif n == 0
      yield([])
    else
      self[1..-1].comb(n) do |x|
        yield(x)
      end
      self[1..-1].comb(n - 1) do |x|
        yield([first] + x)
      end
    end
  end
end


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David A. Black

2008-May-07 21:09 UTC

head link

Re: yields and blocks in Rails

HI --

On Wed, 7 May 2008, Charles wrote:
>
> The below code works just fine in Ruby but I get a LocalJumpError in
> Rails stating "no block given". I thought I knew what a block
was, but
> given the results, I am not so sure. Could someone please offer an
> explanation as to what is going on?
>
> Thanks,
> C.
>
>
> class Array
>  def comb(n = size)
>    if size < n or n < 0
>    elsif n == 0
>      yield([])
>    else
>      self[1..-1].comb(n) do |x|
>        yield(x)
>      end
>      self[1..-1].comb(n - 1) do |x|
>        yield([first] + x)
>      end
>    end
>  end
> end
Can you send a case where you''re calling it and it''s giving
you that
error?


David

-- 
Rails training from David A. Black and Ruby Power and Light:
   INTRO TO RAILS         June 9-12            Berlin
   ADVANCING WITH RAILS   June 16-19           Berlin
   INTRO TO RAILS         June 24-27           London (Skills Matter)
See http://www.rubypal.com for details and updates!

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Charles

2008-May-08 04:34 UTC

head link

Re: yields and blocks in Rails

I was trying to run it in some controller code. I gave up trying to do
anything fancy and just focused on getting something simple to run.
The exception name in the header is LocalJumpError, and the error
message in the box is "no block given". I placed the array extension
as the first thing in the controller file before the controller class.
I call the sample below from within a method in the controller class.

[''a'',''b'',''c'',''d''].comb(3).each
do |element|
    puts element
end

here is where it points to the errors:
app/controllers/courses_controller.rb:11:in `comb''
app/controllers/courses_controller.rb:11:in `comb''
app/controllers/courses_controller.rb:5:in `comb''
app/controllers/courses_controller.rb:10:in `comb''

Because it is the first thing in the file, the line numbers will add
up with the previous code example. They point to the yields.

thanks,
C.



On May 7, 5:09 pm, "David A. Black"
<dbl...-0o/XNnkTkwhBDgjK7y7TUQ@public.gmane.org>
wrote:> HI --
>
>
>
> On Wed, 7 May 2008, Charles wrote:
>
> > The below code works just fine in Ruby but I get a LocalJumpError in
> > Rails stating "no block given". I thought I knew what a
block was, but
> > given the results, I am not so sure. Could someone please offer an
> > explanation as to what is going on?
>
> > Thanks,
> > C.
>
> > class Array
> >  def comb(n = size)
> >    if size < n or n < 0
> >    elsif n == 0
> >      yield([])
> >    else
> >      self[1..-1].comb(n) do |x|
> >        yield(x)
> >      end
> >      self[1..-1].comb(n - 1) do |x|
> >        yield([first] + x)
> >      end
> >    end
> >  end
> > end
>
> Can you send a case where you''re calling it and it''s
giving you that
> error?
>
> David
>
> --
> Rails training from David A. Black and Ruby Power and Light:
>    INTRO TO RAILS         June 9-12            Berlin
>    ADVANCING WITH RAILS   June 16-19           Berlin
>    INTRO TO RAILS         June 24-27           London (Skills Matter)
> Seehttp://www.rubypal.comfor details and updates!--~--~---------~--~----~------------~-------~--~----~
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Mark Bush

2008-May-08 07:54 UTC

head link

Re: yields and blocks in Rails

Charles wrote:>
[''a'',''b'',''c'',''d''].comb(3).each
do |element|
>     puts element
> end
You should get a LocalJumpError with this code in Ruby, too.  Remove the 
".each" and it should be ok.

-- 
Posted via http://www.ruby-forum.com/.

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Charles

2008-May-08 13:40 UTC

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Re: yields and blocks in Rails

Thanks for the eyes :)
with the array output, i was tacking on a .each without even thinking
about it. Comparing the ruby code, i completely glossed over
the .each .

I appreciate it!

C.


On May 8, 3:54 am, Mark Bush
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:> Charles wrote:
> >
[''a'',''b'',''c'',''d''].comb(3).each
do |element|
> >     puts element
> > end
>
> You should get a LocalJumpError with this code in Ruby, too.  Remove the
> ".each" and it should be ok.
>
> --
> Posted viahttp://www.ruby-forum.com/.--~--~---------~--~----~------------~-------~--~----~
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Rails - May 2008 - yields and blocks in Rails

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