From: Yehuda Katz <wycats@gmail.com>
To: rack-devel@googlegroups.com
Subject: Re: "run Proc.new" using "do ... end" fails ("{ }" required)
Date: Fri, 16 Oct 2009 11:02:25 -0700 [thread overview]
Message-ID: <245fb4700910161102n4daa30b2q375f5a398c2f1f15@mail.gmail.com> (raw)
In-Reply-To: <200910161948.44121.ibc@aliax.net>
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This is normal Ruby semantics.
Consider:
method_name another_method do
end
In this case, the "do" is bound to method_name. Now consider:
method_name another_method {
}
In this case, the {} is bound to another_method. Proc.new is just a normal
method, so the above applies.
-- Yehuda
On Fri, Oct 16, 2009 at 10:48 AM, Iñaki Baz Castillo <ibc@aliax.net> wrote:
>
> Hi, the following works:
>
>
> 1 ::Rack::Builder.new do
> 2 map "/" do
> 3 run Proc.new { |env|
> 4 [ 404, {"Content-Type" => "text/plain"}),
> [""] ]
> 5 }
> 6 end
> 7 end
>
>
> but the following gives an error:
>
> 1 ::Rack::Builder.new do
> 2 map "/" do
> 3 run Proc.new do |env|
> 4 [ 404, {"Content-Type" => "text/plain"}),
> [""] ]
> 5 end
> 6 end
> 7 end
>
> /home/me/myfile.rb:3:in `new': tried to create Proc object without a block
> (ArgumentError)
> from /home/me/myfile.rb:3:in `block (2 levels) in core'
> from
> /usr/local/lib/ruby1.9/gems/1.9.1/gems/rack-1.0.0/lib/rack/builder.rb:29:in
> `instance_eval'
> from
> /usr/local/lib/ruby1.9/gems/1.9.1/gems/rack-1.0.0/lib/rack/builder.rb:29:in
> `initialize'
> from
> /usr/local/lib/ruby1.9/gems/1.9.1/gems/rack-1.0.0/lib/rack/builder.rb:46:in
> `new'
> from
> /usr/local/lib/ruby1.9/gems/1.9.1/gems/rack-1.0.0/lib/rack/builder.rb:46:in
> `map'
> from /root/svn_local_copies/OpenXDMS/trunk/lib/rack/core.rb:46:in `block in
> core'
> from
> /usr/local/lib/ruby1.9/gems/1.9.1/gems/rack-1.0.0/lib/rack/builder.rb:29:in
> `instance_eval'
> from
> /usr/local/lib/ruby1.9/gems/1.9.1/gems/rack-1.0.0/lib/rack/builder.rb:29:in
> `initialize'
> from /home/me/myfile.rb:1:in `new'
> ...
>
>
> It fails in ruby 1.8 and 1.9. Why cannot I use "do-end" syntax for a block
> instead of "{ }". Of course, Proc.new does allow "do-end" syntax, so I
> wonder
> if this issue has something to do with Rack itself.
>
>
> Thanks.
>
>
> --
> Iñaki Baz Castillo <ibc@aliax.net>
>
--
Yehuda Katz
Developer | Engine Yard
(ph) 718.877.1325
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next prev parent reply other threads:[~2009-10-16 18:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-16 17:48 "run Proc.new" using "do ... end" fails ("{ }" required) Iñaki Baz Castillo
2009-10-16 18:02 ` Yehuda Katz [this message]
2009-10-16 18:15 ` Iñaki Baz Castillo
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