[Seaside] [newbie!] syntax errors in framework code while debugging/stepping into (kinda urgent)

[Julian Fitzell]

Isolde,

The render and redirect continuations are Continuation-Passing-style
continuations. The render loop (ie. process callbacks, redirect,
render the page, repeat) has been split up into two parts. Each part
is given a key (stored in _k in the URL) and the two types of
continuations call each other back and forth.

At one point, this was done using first-class ("real") continuations
but the loop is so easy to split up by hand, that it was simply
rewritten in continuation passing style to remove the use of
first-class continuations in this case (which makes Seaside more
portable).

I personally found the way the render and redirect continuations were
split quite confusing in 2.8 and you may find them clearer (though
Lukas says he finds them more confusing in 2.9, so maybe not :) ).

Good luck with your presentation.

Julian

On Mon, Jun 29, 2009 at 12:42 PM, <the_damnedest_creature at freenet.de> wrote:
> Hello Julian,
>
> thank you for the quick answer!!
>
> I checked again when squeak would be stuck (meaning, the
> last button on the debugger I pressed is still pressed and I
> can't do anything on squeak anymore), and it's when a new
> context is created. A real pity that doesn't work, but I'm
> really relieved it wasn't my fault.
>
> About the syntax errors: there were more strange ones, so I
> took another fresh image and retyped everything and now it
> works...perhaps I messed something up with the debugging...
>
> And yes, I read that post, it helped indeed and I'm gonna
> show that to my fellow students. :)
> I only read here
> http://www.swa.hpi.uni-potsdam.de/seaside/tutorial that
> render- and redirectContinuations aren't real continuations
> anymore (so they're calling them handlers there), so are
> those then objects which save some states (only those
> variables I told them to save with the states message) in
> e.g. a RenderContext, but don't save the whole context
> chain/stack? If I press the back button that handler knows
> which object's variables should be set to the old values its
> got saved in it's RenderContext, sort of like this?
>
> thanks again, have a nice day
> Isolde
>
>
>  > -----Ursprüngliche Nachricht-----
>  > Von: "Julian Fitzell"
>  > Gesendet: Mon. 29.06.09 (01:31)
>  > An: "Seaside - general discussion"
>  > Betreff: Re: [Seaside] [newbie!] syntax errors in
> framework code while    debugging/stepping into (kinda
> urgent)
>  >
>  > Hi Isolde,
>  >
>  > I'm on my way to bed so I can't give you a detailed
> answer right now
>  > but in general you are not going to be able to step
> through
>  > continuations (at least in Squeak's debugger). Invoking
> a
>  > continuation
>  > results in contexts being rewritten and processes being
> modified and
>  > the debugger just doesn't keep up with that stuff. I'm
> not sure of
>  > the
>  > top of my head why it was "stuck" or exactly what you
> mean by that
>  > but
>  > I'm certainly not surprised you're having trouble.
> Continuations
>  > don't
>  > mix well with exceptions or debuggers.
>  >
>  > If you're having syntax errors within the same debugger
> window, it's
>  > probably because the contexts are out of synch with what
> the debugger
>  > is expecting. If you've closed the debugger and started
> a new session
>  > and are still seeing the problem then I'm not sure
> what's up. Try
>  > quitting the image and trying again.
>  >
>  > Also, I suggest reading
>  >
> http://blog.fitzell.ca/2009/01/seaside-partial-continuations.html
> if
>  > you haven't already as you may find it helpful.
>  >
>  > Perhaps someone will be able to give you more insight
> but that's the
>  > best I can do for the instant.
>  >
>  > Julian
>  >
>
>
>
>
>
>
>
>
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