BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Re: A grid is a bad thing in OO apps? Goto page 1, 2  Next          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Robert Cram Guest Posted: Wed Dec 01, 2004 11:56 am    Post subject: Re: A grid is a bad thing in OO apps? José González D'Amico wrote: Quote: Some time ago I started digging more deeper in the Delphi OO world, specifically researching about OPFs. When I looked at the UI layer, I found that most OPFs avoid data-aware controls to get a clean OO design. My obvious question then was: what kind of controls they use for displaying objects? Looking at papers discussing these OPFs, I found for example TEdit's, TListView's, TTreeView's, etc. used, but never a grid! (I'm not talking about TDBGrid, rather a TStringGrid or similar) Is a grid a bad thing from the OO design point of view? I find that most users are accostumed to them, it seems natural to see tabular information. Thanks for your comments I don't think a grid is is a bad thing from the OO design pointof view. it can get a bit complicated though ;) In quite a few cases I use a grid control to visualize many to many relationships. Columns represent (some) objects from class A, rows represent (some) objects from class B. In the gridcells you can edit the association class. Makes a very nice interface for the user. Back to top Roman Kaßebaum Guest Posted: Wed Dec 01, 2004 12:37 pm    Post subject: Re: A grid is a bad thing in OO apps? José González D'Amico schrieb: Quote: Is a grid a bad thing from the OO design point of view? I find that most users are accostumed to them, it seems natural to see tabular information. In our applications we use an OPF. Naturally, some data should be shown in grids. Therefore we use the orpheus grids which don't store data. The grids have an event OnGetCellData where you can give the data. The disadvantage of the orpheus grids is that they often use pointers. That's why they probably don't work under .net. As a tree view we use the virtual tree view which also doesn't store data. -- Roman Back to top Marc Rohloff [TeamB] Guest Posted: Wed Dec 01, 2004 12:41 pm    Post subject: Re: A grid is a bad thing in OO apps? On 1 Dec 2004 04:25:23 -0700, José González D'Amico wrote: Quote: Is a grid a bad thing from the OO design point of view? I find that most users are accostumed to them, it seems natural to see tabular information. I have heard this theory before. In fact I have been told that grids come from hell. My question is which gives you the better UI since this is more important at the end of the day. We are all used to filling out tabular information. The alternative is generally some sort of list where you then go to the bottom of the screen or to some sort of pop-up window to edit the data. To me this is just plain bad since it means the user has to move their concentration somewhere else. The only problem is when there is too much information to fit well in the grid, so I usually use a combination. -- Marc Rohloff [TeamB] marc rohloff at myrealbox dot com Back to top Bob Dawson Guest Posted: Wed Dec 01, 2004 12:52 pm    Post subject: Re: A grid is a bad thing in OO apps? "José González D'Amico" wrote Quote: that most OPFs avoid data-aware controls to get a clean OO design. Not entirely. I'd say rather that most OPF writers/users avoid an unbroken chain from DB to UI. So for example an OPF is not generally going to allow a grid with an underlying query with liveupdate. What you will find is a query that supports creation of an object collection, and that collection being able to represent itself as an in-memory dataset that can fill a grid. Our apps use the DevEx grid extensively--they're just not linked to queries, but datasets. TClientDataset works for this, as does the DevEx TdxMemData or the excellent and free kbmMemTable. Quote: Is a grid a bad thing from the OO design point of view? Not at all, it's just in OO work the grid is only data-aware if it's linked to an in-memory dataset, not the database, and relies on the objects and object collection rather than bypassing them. Quote: I find that most users are accostumed to them, it seems natural to see tabular information. Quite agree. Whether editing directly in the grid is supported is a separate question. <g> bobD Back to top Joanna Carter (TeamB) Guest Posted: Wed Dec 01, 2004 12:54 pm    Post subject: Re: A grid is a bad thing in OO apps? "José González D'Amico" <joseigd-GOODBYE (AT) SPAM-argentina (DOT) com> a écrit dans le message de news: [email]41adb833 (AT) newsgroups (DOT) borland.com[/email]... Quote: Is a grid a bad thing from the OO design point of view? I find that most users are accostumed to them, it seems natural to see tabular information. IMO a grid is not necessarily a bad thing, it just depends how you implement it. A lot of folks use it as a read-only browsing widget. I have also used it as an editing widget by thinking of it like this : 1. The Grid as a whole is a View on a List whilst browsing. 2. Each row of the grid is a View on a single object with each cell in that row becoming a View on the property that it represents. You need the concept of Current Row that reflects the currently selected object from the list. Using this idea, you should be able to create an edit for use by the cells that has the same behaviour as any other regular edit. If the grid already provides its own editing behaviour, you can intercept the creation of the in-place edit and create a Wrapper or Adapter edit class to 'convert' the in-place behaviour to the expected behaviour for your standard property edits. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Jim Cooper Guest Posted: Wed Dec 01, 2004 2:24 pm    Post subject: Re: A grid is a bad thing in OO apps? José Quote: Looking at papers discussing these OPFs, I found for example TEdit's, TListView's, TTreeView's, etc. used, but never a grid! Well, a TListView can be considered a type of grid, really Quote: Is a grid a bad thing from the OO design point of view? Not in and of itself. They have definitely been overused as a UI paradigm from time to time though :-) I agree with Bob that making grids editable is a separate issue :-) Cheers, Jim Cooper _______________________________________________ Jim Cooper [email]jim (AT) falafelsoft (DOT) com[/email] Falafel Software http://www.falafelsoft.com _______________________________________________ Back to top Franz-Leo Chomse Guest Posted: Wed Dec 01, 2004 2:58 pm    Post subject: Re: A grid is a bad thing in OO apps? Quote: Is a grid a bad thing from the OO design point of view? I find that most users are accostumed to them, it seems natural to see tabular information. It is not a bad thing from the OO design point it is a bad thing from a DB access design point. The basic data access returns a unidirectional result set which has several disadvantages, when combined with a grid. 1. Grid operations need additional management information like position and size of the result set, which is only stable when you are working with a snapshot. 2. Since you can only move forward you have to buffer the data on the client also, since a grid user normally scrolls in both directions. 3. Buffering increases the problems for finding the right record for updates and synchronizing with parallel actions by other users. Regards from Germany Franz-Leo Back to top Bob Dawson Guest Posted: Fri Dec 03, 2004 12:28 pm    Post subject: Re: A grid is a bad thing in OO apps? "José González D'Amico" wrote Quote: Bob and Jim, this is what you implied as not OO-friendly? (if I understood well the "separate issue") Essentially, yes. Grids were not really designed for OO programming--they were designed for direct data manipulation--so adapting them to work well as object manipulators can be extraordinarily complex. When you get done the results may not be close enough to 'normal' grid action to make the effort worthwhile, and it's almost impossible to be sure you've trapped and handled every possible data manipulation in a consistent way. What appears to be happening in the GUI and what's really going on in the OO layer are just too different. Much, much easier to use a call-out frame where the current item of the grid can be edited and the changes then applied to the grid as passive receiver, or in the case of mass actions to exteriorize the operation on a collection selection, and then update the grid afterwards. The grid is a great browsing, grouping, navigation, and selection device. It need not be an entry device. bobD Back to top Joanna Carter (TeamB) Guest Posted: Fri Dec 03, 2004 12:54 pm    Post subject: Re: A grid is a bad thing in OO apps? "José González D'Amico" <joseigd-GOODBYE (AT) SPAM-argentina (DOT) com> a écrit dans le message de news: [email]41b0519c (AT) newsgroups (DOT) borland.com[/email]... Quote: One more question on making grids editable. Bjørge Sæther wrote: Also, programming a grid is hard because there is a lot of actions that may be performed directly (Delete by Ctrl+Del, Insert by Ctrl+Insert, etc.). Also, navigating may cause action invokation, only controllable by the grid internals. Bob and Jim, this is what you implied as not OO-friendly? (if I understood well the "separate issue") As well as using a 'proxy' edit to link to a property of an object, the navigation keys are captured in separate interactors: one for the list and another for the current object. So, for example, Ctrl-Del is intercepted by the list interactor and fires the list deletion, but left and right arrows are handled by the object interactor setting the active property on the object. Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker Back to top Leonardo Pasta Guest Posted: Fri Dec 03, 2004 4:34 pm    Post subject: Re: A grid is a bad thing in OO apps? Hi Jim, I am curious to know how you design Master/Detail interfaces for your objects, like an Order/OrderItem. Usually I design my OrderItem as a Grid, but I still doesn´t use OO in my (production) apps. Thanks, Leonardo Pasta Jim Cooper wrote: Quote: Bob and Jim, this is what you implied as not OO-friendly? Partly. I also have an issue generally with editing in grids - I think it is not very often appropriate. The only time I would even consider it is if all the values fit nicely in the grid without a horizontal scroll bar being required. I generally only like to have one way top edit a given value, and I like to be consistent how I do that throughout an entire application. Back to top Jim Cooper Guest Posted: Fri Dec 03, 2004 4:51 pm    Post subject: Re: A grid is a bad thing in OO apps? Quote: Bob and Jim, this is what you implied as not OO-friendly? Partly. I also have an issue generally with editing in grids - I think it is not very often appropriate. The only time I would even consider it is if all the values fit nicely in the grid without a horizontal scroll bar being required. I generally only like to have one way top edit a given value, and I like to be consistent how I do that throughout an entire application. Cheers, Jim Cooper _______________________________________________ Jim Cooper [email]jim (AT) falafelsoft (DOT) com[/email] Falafel Software http://www.falafelsoft.com _______________________________________________ Back to top Jim Cooper Guest Posted: Sat Dec 04, 2004 3:27 pm    Post subject: Re: A grid is a bad thing in OO apps? Quote: I am curious to know how you design Master/Detail interfaces for your objects, like an Order/OrderItem. Usually I use a grid or similar (there has been a bit of a trend for listviews in my recent projects) for display. Orders and order lines are a good example. Very often order lines have quite a bit of detail associated with them, certainly more than is displayed in the order line list/grid. In those cases I use the grid purely for navigation, and have an embedded form (I don't really like frames) displayed with the values getting updated as the user changes lines. Cheers, Jim Cooper _______________________________________________ Jim Cooper [email]jim (AT) falafelsoft (DOT) com[/email] Falafel Software http://www.falafelsoft.com _______________________________________________ Back to top Joanna Carter (TeamB) Guest Posted: Sat Dec 04, 2004 3:40 pm    Post subject: Re: A grid is a bad thing in OO apps? "Jim Cooper" <jim (AT) falafelsoft (DOT) com> a écrit dans le message de news: 41b1d777$1 (AT) newsgroups (DOT) borland.com... Quote: Usually I use a grid or similar (there has been a bit of a trend for listviews in my recent projects) for display. Orders and order lines are a good example. Very often order lines have quite a bit of detail associated with them, certainly more than is displayed in the order line list/grid. In those cases I use the grid purely for navigation, and have an embedded form (I don't really like frames) displayed with the values getting updated as the user changes lines. Just an idea... How about having the grid in place on the form for navigation only and when you press Ctr-Insert for inserting or Ctrl-Enter for editing, the grid is 'replaced' by a full record editing panel for the currently inserted/editing object ? When the object is accepted/cancelled the area occupied by the 'editor' reverts to showing the grid. Comments ? Joanna -- Joanna Carter (TeamB) Consultant Software Engineer TeamBUG support for UK-BUG TeamMM support for ModelMaker ________ Back to top Jim Cooper Guest Posted: Sat Dec 04, 2004 3:45 pm    Post subject: Re: A grid is a bad thing in OO apps? Quote: Just an idea... Hmmm, I dunno, I think I'd have to see it in action. Cheers, Jim Cooper _______________________________________________ Jim Cooper [email]jim (AT) falafelsoft (DOT) com[/email] Falafel Software http://www.falafelsoft.com _______________________________________________ Back to top Andrea Raimondi Guest Posted: Sat Dec 04, 2004 6:52 pm    Post subject: Re: A grid is a bad thing in OO apps? Joanna Carter (TeamB) wrote: Quote: A lot of folks use it as a read-only browsing widget. I, for one, use a data-aware grid when I simply need, for example, to search in a bunch of records and display results( no editing needed ). Otherwise, I much more prefer a listview - non data-aware. The main problem with grids( imho ) is that they're not flexyble enough to be able to be customized the way you might need. That, imho, applies for practically *all* grids I have come across. 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