cells-devel October 2008

cells-devel@common-lisp.net

3 participants
4 discussions

[cells-devel] Cells: Controlling the way kids are added to a parent ...
by Frank Goenninger 31 Oct '08

31 Oct '08

Hi - I want to control if a kid is added to a parent based on the execution of a check function. The check function is supposed to throw an condition when the check fails. Current use case: Control which classes of kids are added to a parent. I do have a model of class BOM (bill of material) that only can accept classes Assembly and Part as kids. I found two places at which I could insert a call to the check function: function fm-kid-add (higher level interface) function fm-kid-insert (lower level interface) Question now is: Why would one be better than the other? Idea here is based on adding a new slot to class family: (defmodel family (model) ((.kid-slots :cell nil :initform nil :accessor kid-slots :initarg :kid-slots) (.kids :initform (c-in nil) ;; most useful :owning t :accessor kids :initarg :kids) (registry? :cell nil :initform nil :initarg :registry? :accessor registry?) (registry :cell nil :initform nil :accessor registry) ;; added: frgo, 2008-10-30 ----- (kid-add-control-hook :cell nil :initform nil :initarg: kid-add-control-hook))) and then do run the check functions that have been added to the control hook (= list of functions to be funcalled). Right approach? Any comments? (It works but I'd like to know if am on the right track). Thanks for feedback. Cheers Frank

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[cells-devel] Family Registry ? What for ?
by Frank Goenninger 23 Oct '08

23 Oct '08

While inspecting a model I saw the registry? slot - but no registry being assigned ... Which lead to an assertion failure afterwards. So: What for is the registry mechanism? Different families ? Thx for info. Cheers Frank

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[cells-devel] Pentagon of Death [was Re: Vancouver Lisp Users Group meeting for October 2008 - The Nature of Order]
by Kenny 14 Oct '08

14 Oct '08

puchacz wrote: > On Oct 4, 11:03 pm, Kenny <kentil...(a)gmail.com> wrote: > >>Patrick May wrote: >> >>>Kenny <kentil...(a)gmail.com> writes: >> >>>>Patrick May wrote: >> >>>>>Kenny <kentil...(a)gmail.com> writes: >> >>>>>>I wonder if Flash can keep up with compiled JS. You don't mind the >>>>>>Flash requirement? I realize it is ubiquitous enough, but still. >> >>>>> It loads relatively slowly, but once it's loaded it's as fast >>>>>as a desktop app (not surprisingly). I selected it despite the >>>>>Flash requirement because it provided a nice grid control and the >>>>>chart displays I needed. >> >>>>JS frameworks don't have those? >> >>> Some have one, some have the others, some have some other bits I >>>wanted to use. TIBCO's GI was actually my first choice, but there was >>>a bug in Safari that prevented me from using it. >> >>I was just going to say one big win would be insulation from browser >>variability. >> >> >> >> >>>>Or was it more like you had zero reason to avoid Flash (and maybe >>>>already knew it) so there was no reason to hassle with less polished >>>>tools? I suppose you also had the means to acquire the tools. >> >>> Actually, I felt rather dirty using Flash. And not in that good, >>>tingly way. >> >>:) >> >> >> >> >>> Aside from the chart widgets, the tools are free (as in beer). >> >>What's your IDE, Eclipse? >> >> >> >> >>>[ . . . ] >> >>>>No Cells? Are you mad? For a GUI? Celtk and Cells-Gtk (and soon >>>>Xello) will show you how to drive an existing framework with Cells. >> >>> This application is a trading system. If Cells is fast enough, >>>it might be a good choice for the backend. Can I get a response in 10 >>>milliseconds when an order book changes? >> >>10ms is an eternity! I know, I have a feel for that having done >>RoboCells in which we handled realtime inputs spaced at 100ms. >> >>Otherwise, not sure what you are asking. Naturally a very interesting >>question is how long does the functional computation take. But I will >>presume that is in order and what you are asking is if Cells is a pig. >>No. (see "RoboCells"). In fact, Cells helps a bit by magically >>discerning exactly what needs to be updated when X changes. I tried to >>tell the walking dead at ECLM 2008 that Cells is a library about change. >> Practically, this means one has complete control over change, >>including the aforementioned optimization of changing only those things >>that need to change, but also being able to surgically control "oh, I do >>not need to update /that/ every 10ms, I can do it every other unless of >>courese Y changes by 42%". Stuff like that. >> >>Well, if js/html/css get on my nerves I'll take a look at Fex/MXML. Thx >>for the lead. >> >>kt > > > Hi, > > Is Cells able to handle updates in a "diamond scenario"? > > "a": external input > "b": driven from "a" > "c": driven from "a" > "d": driven from "b" and "c" > > As "d" is driven indirectly from a single input "a", and processing of > "b" and "c" may take different time, it is important to wait with > updating of "d" until both "b" and "c" is finished. Otherwise, "d" may > publish its value twice, and the first value would be totally > incorrect, like a huge spike in the series. PWUAHAHAHAHAHHAHAA! I thought I invented that. Philip Eby gave it a more dramatic name when I explained it to him while justifying the Cells mechanism -- the Pentagon of Death, I think it was. Why Pentagon aka 5? I settled on a tougher case in which, eg, d did not depend directly on c, but did so indirectly thru an intermediary depencency c2 which depended on c. Why does this matter? If a changes c needs to be recalculated, period, no question. But C might recompute and come up with the same value, say if A changes from 3 to 6 and C is (mod A 3). In that case we cannot know C2 is obsolete until C runs, and this defeats some algorithms (assuming we have a rule that says "never calculate unecessarily"). I also made it nastier in that...well, it gets complicated, but Cells tracks dynamic dependencies, not lexical, so I cannot just inspect the dependency graph as it stands -- the change to 'a' might make 'd' go after 'c2' for the first time ever in 'd's life. Philip struggled mightily to find a better way than the Cells algorithm, but in the end the Pentagon of Death beat every alternative. Thx for the heads up on the prior art. cheers,ken

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[cells-devel] Cells: File test-cc.lisp missing in CVS
by Frank Goenninger 13 Oct '08

13 Oct '08

Hi Kenny, just noticed your latest commits to CVS for Cells. I dl'ed it and found that both in cells.asd and cells.lpr the file test-cc.lisp is mentioned but missing in the repository. Could you please add this? Thanks! Best, Frank

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cells-devel October 2008