How ring's autoload works?

how-ring-autoload-works.sh

<rationalrevolt> With ring, can some one help me understand why passing a var
                 to run-jetty allows me to reload code and have it reflect
                 immediately? (run-jetty #'handler {:port 8080 :join? false})
                                                                        [12:58]
<nDuff> rationalrevolt: passing the var object means it's involved in the
        lookup, and can be substituted/replaced.                        [12:59]
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    channel #clojure                                                    [13:01]
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<tomoj> &(#'+ 1 2)
<lazybot> ⇒ 3
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                                                                        [13:02]
<rationalrevolt> Doing (+ 1 2) or (#'+ 1 2) gives the same result - but, i'm
                 not seeing whats different
<rationalrevolt> (+ 1 2) would look up the symbol to obtain the var and then
                 invoke it with the arguments                           [13:03]
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    ecmendenhall                                                        [13:04]
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<tomoj> yes, but if you do e.g. (run-jetty handler ...), handler is resolved
        to #'handler, but the var's value, your handler fn, is passed to
        run-jetty
<tomoj> if you redef #'handler later, run-jetty will still have the old fn
<rationalrevolt> (#'+ 1 2) expands to ((var +) 1 2) and (var +) is doing a
                 lookup of + each time (#'+ 1 2) is eval'd - is this correct?
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    #clojure                                                            [13:06]
<tomoj> when you (run-jetty #'handler ...), the thing passed to run-jetty is
        the var, not the fn it points to. when the var is invoked as a
        function it just invokes whichever fn the var currently points to