Yet another reminder why Lisp scoping rules and my feeble lexical brain
don't mesh. I have no opinion as to why or if it's a good thing (Tm) but
it'll burn us old school non Lispers.
On Mon, 2009-07-27 at 05:15 -0400, MenTaLguY wrote:
> I wasn't terribly clear. Let me rephrase -- if you do this:
>
> urls.each do |url|
> link url, :click => Proc.new { window { image url } }
> end
>
> Then every link will open the same image url (since all the created
> Procs reference the same variable, which ends up with the same final
> value). However, if you do this:
>
> def make_image_callback(url)
> Proc.new { window { image url } }
> end
>
> image_urls.each do |image_url|
> link image_url, :click => make_image_callback(image_url)
> end
>
> Then the links should open the correct images, since each call to
> make_image_callback establishes up a separate context for a Proc inside
> to capture, rather than all the Procs sharing the same context and
> variables.
>
> You could also do the call to link itself inside the helper method (as I
> did in my earlier email), but you don't need to.
>
> -mental
>
