What is the correct way to raise an error partway through the stack and detect it in the previous calls to undo things as needed?

I could wrap each @app.call(env) with begin/rescue and raise errors as needed, but that seems a little inelegant. Is there a better way?

Hi, I'm a little confused about how EMPTY_MIDDLEWARE works. It's empty and therefore returns nil. Since it runs last, it makes all of my stacks return nil instead of their current env.

I'm doing the following in my code to work around this:

::Middleware::Runner.const_set :EMPTY_MIDDLEWARE, lambda { |env| env }

Am I misunderstanding something? Doing the whole stack backwards?

Would be good to push a new version to rubygems if & when the outstanding pull requests have been accepted.

I'm not sure exactly what this issue is (or what to do about it), but for some reason building a stack with a parameter out of a hash dies.

require 'rubygems'
require 'middleware'

class MW1
  def initialize(app, value)
    @app = app
    @value = value
  end

  def call(env)
    puts "before"
    @value = @app.call(env)
    puts "after"
  end
end

@config = {'foo' => 'bar'}
var = @config[:var]

pass = Middleware::Builder.new do
  use MW1, var
  use MW1, 3
end

pass.call(nil)

fail = Middleware::Builder.new do
  use MW1, @config['foo']
  use MW1, 3
end

fail.call(nil)

output:

before
before
after
after
fail.rb:28: undefined method `[]' for nil:NilClass (NoMethodError)
    from /Library/Ruby/Gems/1.8/gems/middleware-0.1.0/lib/middleware/builder.rb:38:in `instance_eval'
    from /Library/Ruby/Gems/1.8/gems/middleware-0.1.0/lib/middleware/builder.rb:38:in `initialize'
    from fail.rb:27:in `new'
    from fail.rb:27

I have a project where I would like to setup a reference stack and then make a few different stacks that differ in only a small way from the reference stack. For instance:

stack = Middleware::Builder.new do
  use Trace, "A"
  use Trace, "B"
end

stack2 = stack.dup
stack2.insert_after(2, Trace, "C")

stack2.call
--> A
--> B
--> C
<-- C
<-- B
<-- A

But currently ater I run the above code and I call stack.run, it gives me the same output that stack2 gave me.

If I open a pull request to fix this would you be open to supporting this feature?

middleware depends on redcarpet 2.x. From middleware.gemspec:

  gem.add_development_dependency "redcarpet", "~> 2.1.0"

This version of redcarpet is very old and is vulnerable to cross-site scripting, as described in this blog post: http://danlec.com/blog/bug-in-sundown-and-redcarpet