Folks,
I have not had a single instance of wanting to change global application
behavior at runtime. I cannot think of use case for such a feature.
On the other hand, the idea that your program behavior is stable from the
first HTTP request on makes a lot of sense to me. It means tests work
because the tests don't have to worry about the behavior of the program
changing. The same n steps will lead to the same result.
If anyone can come up with a use case for globally changing program behavior
during program execution, I'm all ears, but barring that, once the boot
phase is over, the stuff in LiftRules should be frozen.
Thanks,
David
On Sun, Dec 14, 2008 at 3:54 AM, Marius <marius.dan...@gmail.com> wrote:
>
>
>
> On Dec 14, 12:53 pm, "Viktor Klang" <viktor.kl...@gmail.com> wrote:
> > On Sun, Dec 14, 2008 at 11:42 AM, Marius <marius.dan...@gmail.com>
> wrote:
> >
> > > On Dec 14, 12:10 pm, "Viktor Klang" <viktor.kl...@gmail.com> wrote:
> > > > On Sun, Dec 14, 2008 at 9:28 AM, Marius <marius.dan...@gmail.com>
> wrote:
> >
> > > > > On Dec 14, 3:02 am, "Jorge Ortiz" <jorge.or...@gmail.com> wrote:
> > > > > > Not to beat a dead horse, but... what's the rationale, again, for
> > > > > throwing
> > > > > > an exception after boot? Is there a real danger to some or all
> > > RulesSeqs
> > > > > > being mutable after boot? If some, then those rules should
> > > selectively be
> > > > > > protected. Even if they're all dangerous, there are better (i.e.,
> > > type
> > > > > safe)
> > > > > > ways of protecting RulesSeqs from mutation than just throwing an
> > > > > exception.
> >
> > > > > This was actually DPP's suggestion. I'm not sure why would someone
> > > > > mutate them after boot but I'm totally opened if there is a strong
> > > > > case for allowing that. I do not have strong feelings about this so
> > > > > changing it would be trivial. Still I kind of like it this way.
> What
> > > > > other ways of protecting mutations after boot are you referring?
> ...
> > > > > something like ignore it and do nothing?
> >
> > > > Hmm, how about "locking" them by havign a paralell lazy val?
> >
> > > > val somePf : RuleSeq = Nil;
> >
> > > > lazy val runtimeSomePf = somePf.toList
> >
> > > > Then prepending/appending on the somePf AFTER runtimeSomePf has been
> > > > dereferenced won't make a difference.
> > > > (runtimeSomePf would be used by Lift internally if that isn't clear
> > > enough
> > > > :) )
> >
> > > Still we'd allow useless strong references on those lists.
> >
> > > > Or another, perhaps more suitable suggestion:
> >
> > > > make boot() have an InitializationContext parameter that's only
> available
> > > in
> > > > the scope of boot, and then the problem should disappear?
> >
> > > How would the problem disappear? ... I mean after boot people would
> > > still be able to add their functions (from API perspective) and they
> > > would be surprised that their functions are not called and yet lift
> > > just allowed them to do that.
> >
> > I meant something like:
> >
> > def boot(val lc : LiftContext) =
> > {
> > //prepend/append,configure everything on lc
> >
> > }
> >
> > And then when the LiftFilter runt boot:
> >
> > {
> > val lc = LiftContext(/*servletContext and stuff goes here*/)
> > boot(lc)
> > LiftRules.init(lc)
> >
> > }
> >
> > And then only have non-append/prependable stuff in LiftRules?
> >
> > But really, what is it a problem that lift is reconfigurable during
> runtime?
> > I thought that was kind of cool?
>
> As I said I don't have strong opinions on this. It was DPP's
> suggestion and personally I kind of like it which does not mean that
> things can not change :) ... AFAIC reconfiguration at runtime does not
> make a whole lot of sense because:
>
> 1. We'd have to expose other functions to allow people to also remove
> their function not only prepend & append them
> 2. I do not see what kinds of problems runtime reconfiguration really
> solve (I'm only referring on the current RulesSeq members). I haven't
> encounter a practical need but if you have please let me know.
> 3. Dynamic behavior can happen inside user's functions without
> allowing runtime reconfiguration.
>
> Just my 2 cents ...
>
> P.S.
> If the general consensus is to remove this restriction I have no
> problem removing it ... so more thoughts/perspectives on this are
> welcomed.
>
>
>
> >
> > Cheers,
> > Viktor
> >
> >
> >
> >
> >
> > > > Cheers,
> > > > Viktor
> >
> > > > > > Nit-pick: why is 'toList' (which just returns 'rules') defined as
> > > > > > private[http] when 'rules' itself is public?
> >
> > > > > Why would you use toList in the lift app code? ...RulesSeq is
> mainly
> > > > > about adding user functions to lift. If "rules" itself is public
> > > > > doesn't necessary mean that it should not have its "private" logic.
> >
> > > > > > Also, if RulesSeq are always made up of either Functions or
> > > > > > PartialFunctions, maybe we should enforce that at a type level,
> and
> > > the
> > > > > > helper methods on Seqs of PFs that now exist in the NamedPF
> object
> > > can be
> > > > > > put in the RulesSeq object.
> >
> > > > > But what would be the benefit? .. except that it would simplify a
> bit
> > > > > how Lift calls these PF's?
> >
> > > > > ... to me distinguishing between functions and partial functions
> here
> > > > > by using Either or even using different RulesSeq traits would not
> > > > > bring much benefits ... but I hope I'm wrong.
> >
> > > > > > --j
> >
> > > > > > On Sat, Dec 13, 2008 at 2:31 PM, Marius <marius.dan...@gmail.com
> >
> > > wrote:
> >
> > > > > > > All,
> >
> > > > > > > I committed a bunch of changes in LiftRules. In a previous
> thread
> > > > > > > Jorge suggested the abstraction of LiftRules variables. Lists
> of
> > > > > > > functions are now abstracted by RulesSeq trait, which contains
> > > prepend
> > > > > > > and append functions. Note that if you're calling
> prepend/append
> > > > > > > functions after boot they will throw an exception. If there are
> > > > > > > compelling reasons not to do this please let us know. This is
> just
> > > a
> > > > > > > mechanism to enforce the use of these functions on startup.
> >
> > > > > > > Br's,
> > > > > > > Marius
> >
> > > > --
> > > > Viktor Klang
> > > > Senior Systems Analyst
> >
> > --
> > Viktor Klang
> > Senior Systems Analyst
> >
>
--
Lift, the simply functional web framework http://liftweb.net
Collaborative Task Management http://much4.us
Follow me: http://twitter.com/dpp
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