Re: block.arity when using each_with_index

Why do you need to check the arity at all? If your method behaves
differently depending on the number of block arguments, it's a clear
sign you need two different methods.

2011/11/23, Bug Free <[e-mail]>:
> Hi,
>
> I have a class with a custom iterator (each) that uses block.arity to
> determine how many arguments to use on the yield. It works well but
> when the caller invokes the iterator via each_with_index, the value
> of block.arity is -1 which wreaks havoc. Does anyone know how to get the
> correct value of block.arity in this situation?\
>
> ruby -v
> ruby 1.9.3p0 (2011-10-30) [x86_64-linux]
>
> Here is the sample code:
> -------------------------------------------
>
> #!/usr/bin/ruby -w
>
> # test block.arity value with each_with_index
>
> class A
>   include Enumerable
>
>   def each( p, &b )
>     puts "arity =3D #{b.arity}"
>     yield 'hello', 'world'
>   end
> end
>
> a =3D A.new
> a.each( 0 ) { |x, y| puts "x =3D #{x}, y =3D #{y}" }
> a.each_with_index( 0 ) { |(x, y), i| puts "x =3D #{x}, y =3D #{y}" }
> ----------------------------------------------------------------
>
> Here is the output:
>
> arity =3D 2
> x =3D hello, y =3D world
> arity =3D -1
> x =3D hello, y =3D world
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

--=20
Wys=C5=82ane z mojego urz=C4=85dzenia przeno=C5=9Bnego

-- Matma Rex