BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Feedback from a Selection          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Ritchie Guest Posted: Thu Nov 27, 2003 2:18 am    Post subject: Feedback from a Selection I am going to have multiple, simultaneous views of the same model. I figured that it would be best to share some sort of IObjectSelection interface amongst them, since objects can be selected from any view, and each view has to respond to a change in selection. I already have many ways of sending a notification. I can either use my notification system for this: ObjectSelection.ChangeSender.AddListener(View as ICOREListener, 'PooledThread' {or 'Synchronous' if I want to wait}); procedure TMyView.Listen(ANotification: ICORENotification); var SelectionChangeNotification : ISelectionChangeNotification; begin if Supports(ANotification,ISelectionChangeNotification, SelectionChangeNotification) then begin // respond to the selection change end; end; Or provide a direct, specialized callback: ObjectSelection.AddChangeSubscriber (View as ISelectionChangeSubscriber); My question is on the sort of notification/callback that an IObjectSelection should provide when the selection is changed (i.e. What should ISelectionChangeNotification have in it?). There are a number of possibilities, here spoken from the lips of the notification facet when it arrives at the view to tell the view what happened: (1) "Something's changed, you go figure it out" (2) "Something's changed, here's the old selection, you go figure it out" (3) (courier #1 arrives) "This one thing has changed"... (courier #2 arrives) "This one thing has changed"... (courier #3 arrives) "This one thing has changed"... (4) "These things have been removed, these things have been added" (5) "These are all the changes, in the precise order that they happened" Anyone got a good rule of thumb as to how to decide amongst such a set of possibilities? -- Ritchie Annand Senior Software Architect Malibu Software & Engineering Ltd. http://www.malibugroup.com http://nimble.nimblebrain.net http://wiki.nimblebrain.net Back to top Joanna Carter (TeamB) Guest Posted: Thu Nov 27, 2003 10:01 am    Post subject: Re: Feedback from a Selection Ritchie wrote: Quote: I am going to have multiple, simultaneous views of the same model. I figured that it would be best to share some sort of IObjectSelection interface amongst them, since objects can be selected from any view, and each view has to respond to a change in selection. As you may have gathered, I use Interactors to respond to user gestures and these are responsible for telling the Selection to change. Because an Interactor can be a State Machine, you can detect whether the Ctrl and/or Shift keys are pressed and Clear/Add/Replace the Selection accordingly from an appropriate State class of the Interactor. Once the Selection has changed, the Model should then notify any Observers. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Ritchie Guest Posted: Thu Nov 27, 2003 8:50 pm    Post subject: Re: Feedback from a Selection In article <3fc5cc4a (AT) newsgroups (DOT) borland.com>, [email]joannac (AT) btinternetXX (DOT) com[/email] says... Quote: Ritchie wrote: | I am going to have multiple, simultaneous views of the same model. I | figured that it would be best to share some sort of IObjectSelection | interface amongst them, since objects can be selected from any view, | and each view has to respond to a change in selection. As you may have gathered, I use Interactors to respond to user gestures and these are responsible for telling the Selection to change. If you want to flesh those Interactors out, you should check out the SubArctic toolkit by Scott Hudson of Carnegie Mellon. I ran across this toolkit looking for geometry management inspiration, but it has a whole pile of interactors and animation objects. It's in preeminently readable Java. Take a look-see. http://www.cc.gatech.edu/gvu/ui/sub_arctic/ Quote: Because an Interactor can be a State Machine, you can detect whether the Ctrl and/or Shift keys are pressed and Clear/Add/Replace the Selection accordingly from an appropriate State class of the Interactor. Once the Selection has changed, the Model should then notify any Observers. *laugh* What the notification should contain was my actual question ;) Quote: Joanna In clicking around on your web page, I noticed a French version; est-ce vrai que tu en parles? Toodles, -- Ritchie Annand Senior Software Architect http://www.malibugroup.com http://nimble.nimblebrain.net http://wiki.nimblebrain.net Back to top Ritchie Guest Posted: Thu Nov 27, 2003 9:23 pm    Post subject: Re: Interactors In article <3fc5cc4a (AT) newsgroups (DOT) borland.com>, [email]joannac (AT) btinternetXX (DOT) com[/email] says... Quote: As you may have gathered, I use Interactors to respond to user gestures and these are responsible for telling the Selection to change. By the way, Joanna - I pulled down the source for the MVP articles a while back, and it looked like it was from the very first articles. Do you have an update? :) -- Ritchie Annand Senior Software Architect http://www.malibugroup.com http://nimble.nimblebrain.net http://wiki.nimblebrain.net Back to top Bryan Crotaz Guest Posted: Fri Nov 28, 2003 12:05 am    Post subject: Re: Feedback from a Selection Quote: Once the Selection has changed, the Model should then notify any Observers. *laugh* What the notification should contain was my actual question I pass a reference-counted interface to a data object. The receiver uses generic methods on this interface to get basic data (like an integer event type or a string name), then queries for more detailed and more specific interfaces if it thinks it understands the notification. By making it ref-counted, the receiver can shove it into a thread-safe queue for later processing by another thread, which gets round the nasty Synchronise stuff on TThread, and means that multiple internal worker threads can communicate using the same Observer mechanism without blocking each other. Bryan Back to top Ritchie Annand Guest Posted: Fri Nov 28, 2003 4:34 am    Post subject: Re: Feedback from a Selection Bryan Crotaz wrote: Hi there, Brian :) Quote: *laugh* What the notification should contain was my actual question ;) I pass a reference-counted interface to a data object. The receiver uses generic methods on this interface to get basic data (like an integer event type or a string name), then queries for more detailed and more specific interfaces if it thinks it understands the notification. My entire framework is reference-counted so far I find it a wonderful way to, amongst other things, get past ownership concerns of objects passed in parameters. My base notification interface is merely a "marker" interface (a string might be a nice add-on), so if you are merely looking for something to have happened, you can leave it alone. Otherwise, you can ask it for a specific notification interface. Certainly is a nice way to get around the lack of polymorphism in parameter lists :) What I was trying to figure out is what sort of detail to put into the interface to the data object: (1) Nothing; leave it as a marker interface and have the listening view rescan the model (2) IModelChange = interface // GUIDs+properties left off for brevity function GetOldModel: IModelObject; end; (3) IModelChange = interface function GetModelChanged: IModelItem; function GetChange: TModelDeltaType; // added or removed end; (4a) IModelChange = interface function GetAddedItemCount: Integer; function GetAddedItem(AIndex: Integer): IModelItem; function GetRemovedItemCount: Integer; function GetRemovedItem(AIndex: Integer): IModelItem; end; (4b) IModelChange = interface function GetAddedItems: IModelItemListIterator; function GetRemovedItems: IModelItemListIterator; end; (5) IModelDelta = interface function GetItem: IModelItem; function GetChange: TModelDeltaType; end; IModelDeltaIterator = iterable list of IModelDelta; IModelChange = interface function GetChanges: IModelDeltaIterator; end; Whew :) Quote: By making it ref-counted, the receiver can shove it into a thread-safe queue for later processing by another thread, which gets round the nasty Synchronise stuff on TThread, and means that multiple internal worker threads can communicate using the same Observer mechanism without blocking each other. Concurrency was another key focal point in the framework. I use a lot of queuing, and enjoy ref-counting for exactly the same reason. For example, I have two interfaces: ICOREExecutor and ICOREExecutable. The former contains a single method: procedure Execute(X: ICOREExecutable), the latter contains a single method: procedure Execute;. I have a thread pool executor that implements ICOREExecutor. When you go MyExecutor.Execute(MyTask), where MyExecutor is a TPooledThreadExecutor, that MyTask goes into a queue. Queue it up twice, no problem. Plenty of queues in the notification system as well. (As for Synchronize, I made a version that you call directly, since ICOREExecutables are -not- thread derivatives themselves :) ----8<---- Based on your interesting comments that parallel some things I've been doing, I'm curious as to what kind of project you're doing, Bryan :) Quote: Bryan -- Ritchie Annand Senior Software Architect Malibu Software & Engineering Ltd. Bus. http://www.malibugroup.com Home. http://nimble.nimblebrain.net Wiki. http://wiki.nimblebrain.net Back to top mrbar Guest Posted: Fri Nov 28, 2003 12:13 pm    Post subject: Re: Feedback from a Selection Hi Ritchie Annand I send a message for your homepage's email address. Could you answer-me please Thanks. Marcos Barreto Back to top Bryan Crotaz Guest Posted: Fri Nov 28, 2003 2:21 pm    Post subject: Re: Feedback from a Selection www.inspiredsignage.com It's a real-time multimedia player for dynamic signage on projectors or plasmas in public environments. Renders 100 layers or text or graphics, each with 3d moves, fades etc, running at 75 frames per second at 1280x1024. Working now on a version that will render up to 20,000x10,000 pixels at 75fps. The current version can also play 3 MPEG2 files or up to 18 divx files simultaneously at full frame rate within those 100 layers. Content changes at run-time, and elements of the schedule are connected to each other to move spatially or temporally as other elements are changed. A template architecture uses interfaces to navigate the element tree to insert data live. There's about 300 classes, several of which exceed 100 lines of declaration with all the interfaces they implement! The "Composer" controller is done with Bold + BoldExpress + Firebird as a web interface. I've worked closely with Neosight to help specify and test Bold Express 2, and the resulting components are brilliant. I couldn't do this without them! Bryan "Ritchie Annand" <ritchiea (AT) spamcop (DOT) net> wrote Quote: Bryan Crotaz wrote: Hi there, Brian :) *laugh* What the notification should contain was my actual question ;) I pass a reference-counted interface to a data object. The receiver uses generic methods on this interface to get basic data (like an integer event type or a string name), then queries for more detailed and more specific interfaces if it thinks it understands the notification. My entire framework is reference-counted so far I find it a wonderful way to, amongst other things, get past ownership concerns of objects passed in parameters. My base notification interface is merely a "marker" interface (a string might be a nice add-on), so if you are merely looking for something to have happened, you can leave it alone. Otherwise, you can ask it for a specific notification interface. Certainly is a nice way to get around the lack of polymorphism in parameter lists :) What I was trying to figure out is what sort of detail to put into the interface to the data object: (1) Nothing; leave it as a marker interface and have the listening view rescan the model (2) IModelChange = interface // GUIDs+properties left off for brevity function GetOldModel: IModelObject; end; (3) IModelChange = interface function GetModelChanged: IModelItem; function GetChange: TModelDeltaType; // added or removed end; (4a) IModelChange = interface function GetAddedItemCount: Integer; function GetAddedItem(AIndex: Integer): IModelItem; function GetRemovedItemCount: Integer; function GetRemovedItem(AIndex: Integer): IModelItem; end; (4b) IModelChange = interface function GetAddedItems: IModelItemListIterator; function GetRemovedItems: IModelItemListIterator; end; (5) IModelDelta = interface function GetItem: IModelItem; function GetChange: TModelDeltaType; end; IModelDeltaIterator = iterable list of IModelDelta; IModelChange = interface function GetChanges: IModelDeltaIterator; end; Whew :) By making it ref-counted, the receiver can shove it into a thread-safe queue for later processing by another thread, which gets round the nasty Synchronise stuff on TThread, and means that multiple internal worker threads can communicate using the same Observer mechanism without blocking each other. Concurrency was another key focal point in the framework. I use a lot of queuing, and enjoy ref-counting for exactly the same reason. For example, I have two interfaces: ICOREExecutor and ICOREExecutable. The former contains a single method: procedure Execute(X: ICOREExecutable), the latter contains a single method: procedure Execute;. I have a thread pool executor that implements ICOREExecutor. When you go MyExecutor.Execute(MyTask), where MyExecutor is a TPooledThreadExecutor, that MyTask goes into a queue. Queue it up twice, no problem. Plenty of queues in the notification system as well. (As for Synchronize, I made a version that you call directly, since ICOREExecutables are -not- thread derivatives themselves :) ----8<---- Based on your interesting comments that parallel some things I've been doing, I'm curious as to what kind of project you're doing, Bryan :) Bryan -- Ritchie Annand Senior Software Architect Malibu Software & Engineering Ltd. Bus. http://www.malibugroup.com Home. http://nimble.nimblebrain.net Wiki. http://wiki.nimblebrain.net Back to top Malte Persike Guest Posted: Fri Nov 28, 2003 4:39 pm    Post subject: Re: Feedback from a Selection Quote: (2) "Something's changed, here's the old selection, you go figure it out" I prefer the second alternative together with an observer mechanism that allows observers to attach to specific changes in the model. The latter is some of the things I always liked about the SmallTalk MVC paradigm. Now, why the (2). The idea of a plain "you figure it out" approach appears to me as a waste of resources considering that the information about what has changed is already there. When a selection changes, it spawns a memento and hands it to the observers which associated to this specific change. There still remains some property-comparing drugwork for the observers but at least this reduces to only those observers which have to adjust to the specific change. More specialized schemes will inevitably result in an explosion of the number of classes (or messages, at least) where in the end it could become necessary to implement a message class for every property of the selection. --- The above e-mail address is not valid. To contact me, please use my real e-mail address: malte AT t DASH online DOT de Back to top Ritchie Annand Guest Posted: Fri Nov 28, 2003 8:19 pm    Post subject: Re: Signage Bryan Crotaz wrote: Quote: www.inspiredsignage.com It's a real-time multimedia player for dynamic signage on projectors or plasmas in public environments. Renders 100 layers or text or graphics, each with 3d moves, fades etc, running at 75 frames per second at 1280x1024. Working now on a version that will render up to 20,000x10,000 pixels at 75fps. The current version can also play 3 MPEG2 files or up to 18 divx files simultaneously at full frame rate within those 100 layers. That sounds like a lot more fun than what I'm doing May I commence being envious now? :) Quote: Content changes at run-time, and elements of the schedule are connected to each other to move spatially or temporally as other elements are changed. A template architecture uses interfaces to navigate the element tree to insert data live. I'm pretty impressed at the claim of live software updates, too :) Quote: There's about 300 classes, several of which exceed 100 lines of declaration with all the interfaces they implement! That's a pretty hefty length for an interface... let me guess - those would be the multimedia equivalents of TCanvas? How many interfaces do you host on a class? How many of them are 'main' interfaces and how many are 'support' (e.g. ILoggable, ISerializable, ...)? Quote: The "Composer" controller is done with Bold + BoldExpress + Firebird as a web interface. I've worked closely with Neosight to help specify and test Bold Express 2, and the resulting components are brilliant. I couldn't do this without them! With BoldRetina on the web side? Quote: Bryan -- Ritchie Annand Back to top Bryan Crotaz Guest Posted: Fri Nov 28, 2003 9:20 pm    Post subject: Re: Signage Quote: That sounds like a lot more fun than what I'm doing May I commence being envious now? Want a job? Just move to London... Quote: Content changes at run-time, and elements of the schedule are connected to each other to move spatially or temporally as other elements are changed. A template architecture uses interfaces to navigate the element tree to insert data live. I'm pretty impressed at the claim of live software updates, too Plugins are wonderful things... Can't reveal my magic technique in public though! Quote: There's about 300 classes, several of which exceed 100 lines of declaration with all the interfaces they implement! That's a pretty hefty length for an interface... LOL - the interfaces are MUCH shorter! Quote: let me guess - those would be the multimedia equivalents of TCanvas? How many interfaces do you host on a class? How many of them are 'main' interfaces and how many are 'support' (e.g. ILoggable, ISerializable, ...)? There's only 3 or 4 whoppers - base classes only. Most are support interfaces. Quote: The "Composer" controller is done with Bold + BoldExpress + Firebird as a web interface. I've worked closely with Neosight to help specify and test Bold Express 2, and the resulting components are brilliant. I couldn't do this without them! With BoldRetina on the web side? "Bold Express Server" now it's version 2. Same stuff though much more fully featured. Bryan Back to top Ritchie Guest Posted: Sat Nov 29, 2003 12:46 am    Post subject: Re: Feedback from a Selection In article <0jsesvg4loaa7ff60teve8m64s7mn5t7jq (AT) 4ax (DOT) com>, [email]me (AT) privacy (DOT) net[/email] says... Quote: (2) "Something's changed, here's the old selection, you go figure it out" I prefer the second alternative together with an observer mechanism that allows observers to attach to specific changes in the model. The latter is some of the things I always liked about the SmallTalk MVC paradigm. When you say specific changes, do you mean specific -kinds- of changes (additions, removals, modifications), or do you mean changes to specific -objects-? Most of the observers I will have here will be views, so they'll be concerned with reflecting the whole model and changes to it. Even an object inspector, if it's multi-selection capable (as Delphi's one is), may have to keep up to date on more than one object, where objects go away, and whether the selection changes. I guess we have something akin to (my apologies for those who don't read in monospace : Model<---Selection ^ ^ Quote: | +---+ +--+ | Views If the Model changes, the Selection and Views should be updated; if the Selection changes, the Views should be updated. I always find it nice to keep the visual state of each View as intact as possible, so, for example, if you have a treeview: - Country (scrolled off the top of the screen) - Leaders - Dictators . Eric Idle + Liberals - Weird . Krusty . Mr. Clean - States ....and decide to delete the Weird branch and add a new dictator, it's nice to keep: - Country (still scrolled off the top of the screen) - Leaders - Dictators . Eric Idle . Jake the Cat From Outer Space + Liberals - States The notification from the model could simply be: 'Model changed' You'd then get your view to scan the entire model looking for what's no longer there and what's been added. This is less well-equipped to detect moves, and scans on a big model could take some time (though likely only enough to make the interface 'jerk' a bit). Or, the notification could say: 'Model changed: Deleted ObjectID=6 (Weird), Added ObjectID=10, Added ObjectID=10's Name "Jake the Cat From Outer Space"' .... Mind you, if you used the above notification to actually *modify* the Model, you could simply pass it along to the Views and the Selection. That would make for a little more interpretation effort on the part of the Views and Selection, but they always have the option of rescanning instead of looking at the model. But then there's the case of doing an Undo. Bah, if it's an Undo, a rescan's not so bad :/ I've quite liked Smalltalk's MVC paradigm myself :) Quote: Now, why the (2). The idea of a plain "you figure it out" approach appears to me as a waste of resources considering that the information about what has changed is already there. When a selection changes, it spawns a memento and hands it to the observers which associated to this specific change. There still remains some property-comparing drugwork for the observers but at least this reduces to only those observers which have to adjust to the specific change. More specialized schemes will inevitably result in an explosion of the number of classes (or messages, at least) where in the end it could become necessary to implement a message class for every property of the selection. I have only Entities and Attributes in the scheme I'm thinking of, and neither of them have specializations :) I'll have to figure out a compromise between message-per-individual- change and message-per-change-block. One other thing I'm trying to consider (to keep the visual interface relatively snappy) is how to make the updates asynchronous... and therefore, how to make the Views resistant to mismatches between the Model and View (e.g. no access violations when you try editing something that no longer exists but hasn't been updated visually yet) Thanks for the discussion, folks; getting things out on the table *really* helps :) Thanks for the thoughts, Malte :) -- Ritchie Annand Senior Software Architect http://www.malibugroup.com http://nimble.nimblebrain.net http://wiki.nimblebrain.net Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi OO design All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.