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• Wrapping a point-to-point link

  - by user3712955

  I'm using a pair of IP radios (non-WiFi) to bridge my office engineering LAN (172.0.0.0/8) to a lab in another building. The radios work fine, but they expose a web management interface I'd like to hide, and they also generate traffic (ARP, STP, and more) that I need to keep off my (very, very clean) LAN segments. I have some ARM-Linux boards (similar to Beagle/Panda/RasPi) running Ubuntu, and I've put one at each end of the link, between the radio and the LAN. Each of the boards has 2 wired Ethernet interfaces, eth0 and eth1. The LAN segments are connected to eth0, and the radios are connected to eth1. I'd like to accomplish the following: Keep radio-originated traffic off my LAN segments! Hide all services provided by the radio (web, ssh, etc.) Transparently pass all traffic between the LAN segments (including things like ARP). The above also applies to the ARM-Linux boards: No stray traffic my LAN from them either! I'd like the system to look like a switch: LAN packets arriving at one eth0 appear at the other. And neither eth0 should have an IP address: The working system should behave like a CAT6 cable with some latency (instead of ARM boards and radios). Unfortunately, I'm confused about how to properly configure the ARM Ubuntu systems. What I'm guessing I need is a bridge on each board (br0?) and a VLAN (vlan0 or eth0.0?) to isolate the LAN traffic from everything else as it passes through the ARM boards and the radios. Then I need some kind of a firewall to block sending anything out eth0 that isn't from the other eth0 (via the VLAN). I've looked at the ip and ebtables commands (especially -t broute). While the concepts sorta-kinda make sense, I'm completely lost in the details. Edit: In the perverse case that a system on one of my LAN segments has the same IP address as one of the radios, or as eth1 on the ARM-Ubuntu boards, a VLAN won't work. Which I believe means I need to tunnel all traffic between the two eth0 interfaces to get that "like a wire" behavior. Help? Finally, I'd like to have a way to temporarily expose services on the ARM boards (ssh) and the radios (web) for maintenance purposes. Ideally, it would expose an IP address with ssh available on port 22. Once connected, I figure I'd start an X11 session and run a browser on the ARM board to access the radios. Or something. I could login via the console to enable/disable this, or perhaps could use a GPIO to trigger a script. I feel I've identified most of the pieces needed to make all this happen, but I have no idea how to combine them to make a working system. Thanks!

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• WPF: Setting DataContext of a UserControl with Binding not working in XAML

  - by Grant Crofton

  Hi, I'm trying to get my first WPF app working using MVVM, and I've hit a little binding problem. The setup is that I have a view & viewModel which holds User details (the parent), and to try and keep things simple I've put a section of that view into a separate view & viewModel (the child). The child view is defined as a UserControl. The issue I'm having is how to set the DataContext of the child view (the UserControl). My parent ViewModel has a property which exposes the child ViewModel, like so: class ParentViewModel: INotifyPropertyChanged { public ChildViewModel childViewModel { get; set; } //... } In the XAML for my parent view (which has it's DataContext set to the ParentViewModel), I try to set the DataContext of the child view as follows: <views:ChildView x:Name="ChildView" DataContext="{Binding childViewModel}"/> However, this doesn't work. The DataContext of the child view is set to the same DataContext as the parent view (i.e. the ParentViewModel), as if I wasn't setting it at all. I also tried setting the DataContext in the child view itself, which also doesn't work: <UserControl x:Class="DietRecorder.Client.View.ChildView" DataContext="childViewModel" I have found a couple of ways around this. In the child view, I can bind everything by including the ChildViewModel in the path: <SomeControl Visibility="{Binding Path=childViewModel.IsVisible}"> but I don't want the child view to have this level of awareness of the hierarchy. Setting the DataContext in code also works - however, I have to do this after showing the parent view, otherwise the DataContext just gets overwritten when I call Show(): parentView.Show(); parentView.ChildView.DataContext = parentViewModel.childViewModel; This code also makes me feel uneasy, what with the LOD violation and all. It's just the DataContext that seems to be the problem - I can bind other things in the child, for example I tried binding the FontSize to an int property just to test it: <views:ChildView x:Name="ChildView" FontSize="{Binding Path=someVal}"/> And that works fine. But I'm sure binding the DataContext should work - I've seen similar examples of this kind of thing. Have I missed something obvious here? Is there a reason this won't work? Is there a spelling mistake somewhere? (I renamed things for your benefit so you won't be able to help me there anyway). Any thoughts welcome. Thanks, Grant

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• jquery ui draggable elements not 'draggable' outside of scrolling div

  - by Stu

  hello all, i am super stumped. i have many elements (floating href tags) in a div with a set height/width, with scroll set to "overflow: auto" in the css. this is the structure of the divs: <div id="tagFun_div_main"> <div id="tf_div_tagsReturn"> <!-- all the draggable elements go in here, the parent div scolls --> </div> <div id=" tf_div_tagsDrop"> <div id="tf_dropBox"></div> </div></div> the parent div's, 'tf_div_tagsReturn' and 'tf_div_tagsDrop' will ultimately float next to each other. here is the jquery which is run after all of the 'draggable' elements have been created with class name 'tag_cell', : $(function() { $(".tag_cell").draggable({ revert: 'invalid', scroll: false, containment: '#tagFun_div_main' }); $("#tf_dropBox").droppable({ accept: '.tag_cell', hoverClass: 'tf_dropBox_hover', activeClass: 'tf_dropBox_active', drop: function(event, ui) { GLOBAL_ary_tf_tags.push(ui.draggable.html()); tagFun_reload(); } }); }); as i stated above, the draggable elements are draggable within div 'tf_div_tagsReturn', but they do not visually drag outside of that parent div. worthy to note, if i am dragging one of the draggable elements, and move the mouse over the droppable div, with id 'tf_dropBox', then the hoverclass is fired, i just can't see the draggable element any more. thank you very much for any advice on helping me find a solution. this is my first run at using jquery, so hopefully i am just missing something super obvious. i've been reading the documentation and searching forums thus far to no prevail :( thank you for your time. UPDATE: many thanks to Jabes88 for providing the solution which allowed me to achieve the functionality i was looking for, here is what my jquery ended up looking like, feel free to critique it, as i am new to jquery. $(function() { $(".tag_cell").draggable({ revert: 'invalid', scroll: false, containment: '#tagFun_div_main', helper: 'clone', start : function() { this.style.display="none"; }, stop: function() { this.style.display=""; } }); $(".tf_dropBox").droppable({ accept: '.tag_cell', hoverClass: 'tf_dropBox_hover', activeClass: 'tf_dropBox_active', drop: function(event, ui) { GLOBAL_ary_tf_tags.push(ui.draggable.html()); tagFun_reload(); } }); });

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• WPF Dynamic Layout with ItemsControl and Grid

  - by Jason Williams

  I am creating a WPF form. One of the requirements is that it have a sector-based layout so that a control can be explicitly placed in one of the sectors/cells. I have created a tic-tac-toe example below to convey my problem: There are two types and one base type: public class XMoveViewModel : MoveViewModel { } public class OMoveViewModel : MoveViewModel { } public class MoveViewModel { public int Row { get; set; } public int Column { get; set; } } The DataContext of the form is set to an instance of: public class MainViewModel : ViewModelBase { public MainViewModel() { Moves = new ObservableCollection<MoveViewModel>() { new XMoveViewModel() { Row = 0, Column = 0 }, new OMoveViewModel() { Row = 1, Column = 0 }, new XMoveViewModel() { Row = 1, Column = 1 }, new OMoveViewModel() { Row = 0, Column = 2 }, new XMoveViewModel() { Row = 2, Column = 2} }; } public ObservableCollection<MoveViewModel> Moves { get; set; } } And finally, the XAML looks like this: <Window.Resources> <DataTemplate DataType="{x:Type vm:XMoveViewModel}"> <Image Source="XMove.png" Grid.Row="{Binding Path=Row}" Grid.Column="{Binding Path=Column}" Stretch="None" /> </DataTemplate> <DataTemplate DataType="{x:Type vm:OMoveViewModel}"> <Image Source="OMove.png" Grid.Row="{Binding Path=Row}" Grid.Column="{Binding Path=Column}" Stretch="None" /> </DataTemplate> </Window.Resources> <Grid> <ItemsControl ItemsSource="{Binding Path=Moves}"> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <Grid ShowGridLines="True"> <Grid.RowDefinitions> <RowDefinition /> <RowDefinition /> <RowDefinition /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition /> <ColumnDefinition /> <ColumnDefinition /> </Grid.ColumnDefinitions> </Grid> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> </ItemsControl> </Grid> What was not so obvious to me when I started was that the ItemsControl element actually wraps each item in a container, so my Grid.Row and Grid.Column bindings are ignored since the images are not directly contained within the grid. Thus, all of the images are placed in the default Row and Column (0, 0). What is happening: The desired result: So, my question is this: how can I achieve the dynamic placement of my controls in a grid? I would prefer a XAML/Data Binding/MVVM-friendly solution. Thanks.

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• MVVM pattern and nested view models - communication and lookup lists

  - by LostInWPF

  I am using Prism for a new application that I am creating. There are several lookup lists that will be used in several places in the application. Therefore it makes sense to define it once and use that everywhere I need that functionality. My current solution is to use typed data templates to render the controls inside a content control. <DataTemplate DataType={x:Type ListOfCountriesViewModel}> <ComboBox ItemsSource={Binding Countries} SelectedItem="{Binding SelectedCountry"/> </DataTemplate> <DataTemplate DataType={x:Type ListOfRegionsViewModel}> <ComboBox ItemsSource={Binding Countries} SelectedItem={Binding SelectedRegion} /> </DataTemplate> public class ParentViewModel { SelectedCountry get; set; SelectedRegion get; set; ListOfCountriesViewModel CountriesVM; ListOfRegionsViewModel RgnsVM; } Then in my window I have 2 content controls and the rest of the controls <ContentControl Content="{Binding CountriesVM}"></ContentControl> <ContentControl Content="{Binding RgnsVM}"></ContentControl> <Rest of controls on view> At the moment I have this working and the SelectedItems for the combo boxes are publising events via EventAggregator from the child view models which are then subscribed to in the parent view model. I am not sure that this is the best way to go as I can imagine I would end up with a lot of events very quickly and it will become unwieldy. Also if I was to use the same view model on another window it will publish the event and this parent viewmodel is subscribed to it which could have unintended consequences. My questions are :- Is this the best way to put lookup lists in a view which can be re-used across screens? How do I make it so that the combobox which is bound to the child viewmodel sets the relevant property on the parent viewmodel without using events / mediator. e.g in this case SelectedCountry for example? Any alternative implementation proposals for what I am trying to do? I have a feeling I am missing something obvious and there is so much info it is hard to know what is right so any help would be most gratefully received.

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• iPad application crash in Apple review - cannot replicate in simulator, have crash log

  - by Mike

  I am clearly missing something obvious here and would really appreciate some input. I have tried repeatedly to submit an application to Apple (iPad in this case) that is crashing on their end when testing but I cannot replicated the situation on my end (obviously I only have the damned simulator to work with at this point). The crash log is as follows: Date/Time: 2010-04-01 05:39:47.226 -0700 OS Version: iPhone OS 3.2 (7B367) Report Version: 104 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x00000000, 0x00000000 Crashed Thread: 0 Thread 0 Crashed: 0 libSystem.B.dylib 0x000790a0 __kill + 8 1 libSystem.B.dylib 0x00079090 kill + 4 2 libSystem.B.dylib 0x00079082 raise + 10 3 libSystem.B.dylib 0x0008d20a abort + 50 4 libstdc++.6.dylib 0x00044a1c __gnu_cxx::__verbose_terminate_handler() + 376 5 libobjc.A.dylib 0x000057c4 _objc_terminate + 104 6 libstdc++.6.dylib 0x00042dee __cxxabiv1::__terminate(void (*)()) + 46 7 libstdc++.6.dylib 0x00042e42 std::terminate() + 10 8 libstdc++.6.dylib 0x00042f12 __cxa_throw + 78 9 libobjc.A.dylib 0x000046a4 objc_exception_throw + 64 10 CoreFoundation 0x00090c6e +[NSException raise:format:arguments:] + 74 11 CoreFoundation 0x00090d38 +[NSException raise:format:] + 28 12 Foundation 0x00002600 -[NSCFDictionary setObject:forKey:] + 184 13 iPadMosaic 0x00003282 -[iPadMosaicViewController getAlbumThumbs] (iPadMosaicViewController.m:468) 14 Foundation 0x000728fe __NSFireDelayedPerform + 314 15 CoreFoundation 0x00022d1c CFRunLoopRunSpecific + 2092 16 CoreFoundation 0x000224da CFRunLoopRunInMode + 42 17 GraphicsServices 0x000030d4 GSEventRunModal + 108 18 GraphicsServices 0x00003180 GSEventRun + 56 19 UIKit 0x000034c2 -[UIApplication _run] + 374 20 UIKit 0x000019ec UIApplicationMain + 636 21 iPadMosaic 0x00002234 main (main.m:14) 22 iPadMosaic 0x00002204 start + 32 My understanding here is that I am botching the Dictionary add somehow. The relevant lines of code are: for (NSDictionary *album in self.albumList) { // Get image for each album cover UIImage *albumCover; // Loop through photos to get URL of cover based on photo ID match NSString *coverURL = @""; for (NSDictionary *photo in self.photoList) { if ([[photo objectForKey:@"pid"] isEqualToString:[album objectForKey:@"cover_pid"]]) { coverURL = [photo objectForKey:@"src"]; } } NSURL *albumCoverURL = [NSURL URLWithString:coverURL]; NSData *albumCoverData = [NSData dataWithContentsOfURL:albumCoverURL]; albumCover = [UIImage imageWithData:albumCoverData]; if (albumCover == nil || albumCover == NULL) { //NSLog(@"No album cover for some reason"); albumCover = [UIImage imageNamed:@"noImage.png"]; } [[self.albumList objectAtIndex:albumCurrent] setObject:albumCover forKey:@"coverThumb"]; } This is part of a loop that runs over the existing dictionaries stored in an array. If retrieving the album cover fails for some reason the object is filled with a default image and then added. The last line of the code is what's showing up in the crash log. It runs fine in the simulator but crashes 100% in testing on device apparently. Can anyone tell me what I am missing here?

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• facebook connect for android returns a blank login screen?

  - by jonney

  Hi, i am trying to use the old facebook connect authentication to authenticate my android client to get the necessary session id's and other credentials thats needed to start using the web service of facebook. the issue i am having is that when my android application launces and tries to load the login page for facebook, that very same login page is blank and it only displays the the facebook logo as the title of the screen. No login fields or buttons are visible leaving me nowhere to login and authenticate a user. i have tried two API's one is facebook connect api for android http://code.google.com/p/fbconnect-android/ and the other one is the official android facebook sdk that is recommended to be used instead of the previous one i have just mentioned https://github.com/facebook/facebook-android-sdk/ . please see the image below of how it looks like on my app. Here is code that uses the latest android sdk facebook: /** * Authenticate facebook network */ private void authenticateFacebook() { // TODO: move this away from this activty class into some kind of // helper/wrapper class Log.d(TAG, "Clicked on the facebook"); Facebook facebook = new Facebook(OAUTH_KEY_FACEBOOK_API); facebook.authorize(this, new AuthorizeListener()); } class AuthorizeListener implements DialogListener{ @Override public void onComplete(Bundle values) { // TODO Auto-generated method stub Log.d(TAG, "finished authorizing facebook user"); } @Override public void onFacebookError(FacebookError e) { // TODO Auto-generated method stub } @Override public void onError(DialogError e) { // TODO Auto-generated method stub } @Override public void onCancel() { // TODO Auto-generated method stub } } And a simple example of how to use it: http://developers.facebook.com/docs/guides/mobile/ My code is more or less identical to the above example. edit: i did not catch what logcat was inputing in my first attempted at my code above but their was no exceptions or warnings thrown at the time. just a blank page. i then tried it again and diddnt touch my code and what happens now is that a loading dialogue view pops up and stays their for a few minutes until the facebook windows disapears and the logcat outputs the error below: 11-18 17:26:19.913: DEBUG/Facebook-WebView(783): Webview loading URL: https://www.facebook.com/dialog/oauth?type=user_agent&redirect_uri=fbconnect%3A%2F%2Fsuccess&display=touch&client_id=e??????????????????? 11-18 17:27:01.756: DEBUG/Facebook-authorize(783): Login failed: com.kc.unity.agent.util.oauth.facebook.DialogError: The connection to the server was unsuccessful. 11-18 17:27:01.783: DEBUG/Facebook-WebView(783): Webview loading URL: https://www.facebook.com/dialog/oauth?type=user_agent&redirect_uri=fbconnect%3A%2F%2Fsuccess&display=touch&client_id=??????????????? please note that the client id i have amended for obvious reasons but the rest of the logcat is untouched

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• Why is drawing to OnPaint graphics faster than image graphics?

  - by Tesserex

  I'm looking for a way to speed up the drawing of my game engine, which is currently the significant bottleneck, and is causing slowdowns. I'm on the verge of converting it over to XNA, but I just noticed something. Say I have a small image that I've loaded. Image img = Image.FromFile("mypict.png"); We have a picturebox on the screen we want to draw on. So we have a handler. pictureBox1.Paint += new PaintEventHandler(pictureBox1_Paint); I want our loaded image to be tiled on the picturebox (this is for a game, after all). Why on earth is this code: void pictureBox1_Paint(object sender, PaintEventArgs e) { for (int y = 0; y < 16; y++) for (int x = 0; x < 16; x++) e.Graphics.DrawImage(image, x * 16, y * 16, 16, 16); } over 25 TIMES FASTER than this code: Image buff = new Bitmap(256, 256, PixelFormat.Format32bppPArgb); // actually a form member void pictureBox1_Paint(object sender, PaintEventArgs e) { using (Graphics g = Graphics.FromImage(buff)) { for (int y = 0; y < 16; y++) for (int x = 0; x < 16; x++) g.DrawImage(image, x * 16, y * 16, 16, 16); } e.Graphics.DrawImage(buff, 0, 0, 256, 256); } To eliminate the obvious, I've tried commenting out the last e.Graphics.DrawImage (which means I don't see anything, but it gets rid a call that isn't in the first example). I've also left in the using block (needlessly) in the first example, but it's still just as blazingly fast. I've set properties of g to match e.Graphics - things like InterpolationMode, CompositingQuality, etc, but nothing I do bridges this incredible gap in performance. I can't find any difference between the two Graphics objects. What gives? My test with a System.Diagnostics.Stopwatch says that the first code snippet runs at about 7100 fps, while the second runs at a measly 280 fps. My reference image is VS2010ImageLibrary\Objects\png_format\WinVista\SecurityLock.png, which is 48x48 px, and which I modified to be 72 dpi instead of 96, but those made no difference either.

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• Entity Framework won't SaveChanges on new entity with two-level relationship

  - by Tim Rourke

  I'm building an ASP.NET MVC site using the ADO.NET Entity Framework. I have an entity model that includes these entities, associated by foreign keys: Report(ID, Date, Heading, Report_Type_ID, etc.) SubReport(ID, ReportText, etc.) - one-to-one relationship with Report. ReportSource(ID, Name, Description) - one-to-many relationship with Sub_Report. ReportSourceType(ID, Name, Description) - one-to-many relationship with ReportSource. Contact (ID, Name, Address, etc.) - one-to-one relationship with Report_Source. There is a Create.aspx page for each type of SubReport. The post event method returns a new Sub_Report entity. Before, in my post method, I followed this process: Set the properties for a new Report entity from the page's fields. Set the SubReport entity's specific properties from the page's fields. Set the SubReport entity's Report to the new Report entity created in 1. Given an ID provided by the page, look up the ReportSource and set the Sub_Report entity's ReportSource to the found entity. SaveChanges. This workflow succeeded just fine for a couple of weeks. Then last week something changed and it doesn't work any more. Now instead of the save operation, I get this Exception: UpdateException: "Entities in 'DIR2_5Entities.ReportSourceSet' participate in the 'FK_ReportSources_ReportSourceTypes' relationship. 0 related 'ReportSourceTypes' were found. 1 'Report_Source_Types' is expected." The debug visualizer shows the following: The SubReport's ReportSource is set and loaded, and all of its properties are correct. The Report_Source has a valid ReportSourceType entity attached. In SQL Profiler the prepared SQL statement looks OK. Can anybody point me to what obvious thing I'm missing? TIA Notes: The Report and SubReport are always new entities in this case. The Report entity contains properties common to many types of reports and is used for generic queries. SubReports are specific reports with extra parameters varying by type. There is actually a different entity set for each type of SubReport, but this question applies to all of them, so I use SubReport as a simplified example.

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• Multi-step Workflows: make Workflow A depend on results of Workflow B and/or Workflow C

  - by Joey

  I have been tasked with creating a Software Installation Approval section for our Intranet. When a person requests that a particular piece of software be installed on their workstation, we need to get IT approval and then business approval. Once those are obtained, it is to be installed. I am using Sharepoint Designer to do this. I have List A, where the user enters the information on the requested software. Workflow A then creates a Task in List B, which is then assigned to the IT approver. Workflow B works on List B on item creation, setting the due dates, titles, and other fields, and then pauses until the due date. The IT approver works with the business side and completes the task. Once List B task is complete, the item in List A should be marked as complete -- I have everything up to this point working fine. I want to make this more robust in 2 ways. As the only real option is to mark List B task as "completed", which essentially means "Approved", we have no way of really denying a request. What I want to add is the option to approve or deny a request through the task on List B -- if it is approved, I want the item in List A to continue to show "In Progress" with a custom status of "Approved", and I want to create a new task for software installation; once the installation task is marked as completed, then I want List A to show "Completed" with a status of "Installed". If it is denied, I want the item in List A to show as "Completed", with a status of "Denied". The problem is, I'm not even sure where to start making these modifications. Creating and modifying the custom status fields isn't that big of an issue -- I have messed around with this and I'm fairly confident I can do this easily. My main concern is that I know I will need a Workflow C, but I don't know where or how to trigger this to get the results I need. I've managed to get Workflows A and B working fine, but anything beyond this is really pushing the limit of my knowledge. It's probably obvious that I am rather new to Sharepoint workflows. I was very much thrust into this position and I am still feeling my way around. Thanks in advance for any help!

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• Which functions in the C standard library commonly encourage bad practice?

  - by Ninefingers

  Hello all, This is inspired by this question and the comments on one particular answer in that I learnt that strncpy is not a very safe string handling function in C and that it pads zeros, until it reaches n, something I was unaware of. Specifically, to quote R.. strncpy does not null-terminate, and does null-pad the whole remainder of the destination buffer, which is a huge waste of time. You can work around the former by adding your own null padding, but not the latter. It was never intended for use as a "safe string handling" function, but for working with fixed-size fields in Unix directory tables and database files. snprintf(dest, n, "%s", src) is the only correct "safe strcpy" in standard C, but it's likely to be a lot slower. By the way, truncation in itself can be a major bug and in some cases might lead to privilege elevation or DoS, so throwing "safe" string functions that truncate their output at a problem is not a way to make it "safe" or "secure". Instead, you should ensure that the destination buffer is the right size and simply use strcpy (or better yet, memcpy if you already know the source string length). And from Jonathan Leffler Note that strncat() is even more confusing in its interface than strncpy() - what exactly is that length argument, again? It isn't what you'd expect based on what you supply strncpy() etc - so it is more error prone even than strncpy(). For copying strings around, I'm increasingly of the opinion that there is a strong argument that you only need memmove() because you always know all the sizes ahead of time and make sure there's enough space ahead of time. Use memmove() in preference to any of strcpy(), strcat(), strncpy(), strncat(), memcpy(). So, I'm clearly a little rusty on the C standard library. Therefore, I'd like to pose the question: What C standard library functions are used inappropriately/in ways that may cause/lead to security problems/code defects/inefficiencies? In the interests of objectivity, I have a number of criteria for an answer: Please, if you can, cite design reasons behind the function in question i.e. its intended purpose. Please highlight the misuse to which the code is currently put. Please state why that misuse may lead towards a problem. I know that should be obvious but it prevents soft answers. Please avoid: Debates over naming conventions of functions (except where this unequivocably causes confusion). "I prefer x over y" - preference is ok, we all have them but I'm interested in actual unexpected side effects and how to guard against them. As this is likely to be considered subjective and has no definite answer I'm flagging for community wiki straight away. I am also working as per C99.

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• T-SQL selecting values that match ISNUMERIC and also are within a specified range. (plus Linq-to-sql

  - by Toby

  I am trying to select rows from a table where one of the (NVARCHAR) columns is within a numeric range. SELECT ID, Value FROM Data WHERE ISNUMERIC(Value) = 1 AND CONVERT(FLOAT, Value) < 66.6 Unfortunately as part of the SQL spec the AND clauses don't have to short circuit (and don't on MSSQL Server EE 2008). More info: http://stackoverflow.com/questions/789231/is-the-sql-where-clause-short-circuit-evaluated My next attempt was to try this to see if I could achieve delayed evaluation of the CONVERT SELECT ID, Value FROM Data WHERE (CASE WHEN ISNUMERIC(Value) = 1 THEN CONVERT(FLOAT, Value) < 66.6 ELSE 0 END) but I cannot seem to use a < (or any comparison) with the result of a CONVERT. It fails with the error Incorrect syntax near '<'. I can get away with SELECT ID, CONVERT(FLOAT, Value) AS Value FROM Data WHERE ISNUMERIC(Value) = 1 So the obvious solution is to wrap the whole select statement in another SELECT and WHERE and return the converted values from the inner select and filter in there where of the outer select. Unfortunately this is where my Linq-to-sql problem comes in. I am filtering not only by one range but potentialy by many, or just by the existance of the record (there are some date range selects and comparisons I've left out.) Essentially I would like to be able to generate something like this: SELECT ID, TypeID, Value FROM Data WHERE (TypeID = 4 AND ISNUMERIC(Value) AND CONVERT(Float, Value) < 66.6) OR (TypeID = 8 AND ISNUMERIC(Value) AND CONVERT(Float, Value) > 99) OR (TypeID = 9) (With some other clauses in each of those where options.) This clearly doesn't work if I filter out the non-ISNUMERIC values in an inner select. As I mentioned I am using Linq-to-sql (and PredicateBulider) to build up these queries but unfortunately Datas.Where(x => ISNUMERIC(x.Value) ? Convert.ToDouble(x.Value) < 66.6 : false) Gets converted to this which fails the initial problem. WHERE (ISNUMERIC([t0].[Value]) = 1) AND ((CONVERT(Float,[t0].[Value])) < @p0) My last resort will have to be to outer join against a double select on the same table for each of the comparisons but this isn't really an idea solution. I was wondering if anyone has run into similar issues before?

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• Union struct produces garbage and general question about struct nomenclature

  - by SoulBeaver

  I read about unions the other day( today ) and tried the sample functions that came with them. Easy enough, but the result was clear and utter garbage. The first example is: union Test { int Int; struct { char byte1; char byte2; char byte3; char byte4; } Bytes; }; where an int is assumed to have 32 bits. After I set a value Test t; t.Int = 7; and then cout cout << t.Bytes.byte1 << etc... the individual bytes, there is nothing displayed, but my computer beeps. Which is fairly odd I guess. The second example gave me even worse results. union SwitchEndian { unsigned short word; struct { unsigned char hi; unsigned char lo; } data; } Switcher; Looks a little wonky in my opinion. Anyway, from the description it says, this should automatically store the result in a high/little endian format when I set the value like Switcher.word = 7656; and calling with cout << Switcher.data.hi << endl The result of this were symbols not even defined in the ASCII chart. Not sure why those are showing up. Finally, I had an error when I tried correcting the example by, instead of placing Bytes at the end of the struct, positioning it right next to it. So instead of struct {} Bytes; I wanted to write struct Bytes {}; This tossed me a big ol' error. What's the difference between these? Since C++ cannot have unnamed structs it seemed, at the time, pretty obvious that the Bytes positioned at the beginning and at the end are the things that name it. Except no, that's not the entire answer I guess. What is it then?

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• Is MVVM pointless?

  - by joebeazelman

  Is orthodox MVVM implementation pointless? I am creating a new application and I considered Windows Forms and WPF. I chose WPF because it's future-proof and offer lots of flexibility. There is less code and easier to make significant changes to your UI using XAML. Since the choice for WPF is obvious, I figured that I may as well go all the way by using MVVM as my application architecture since it offers blendability, separation concerns and unit testability. Theoretically, it seems beautiful like the holy grail of UI programming. This brief adventure; however, has turned into a real headache. As expected in practice, I’m finding that I’ve traded one problem for another. I tend to be an obsessive programmer in that I want to do things the right way so that I can get the right results and possibly become a better programmer. The MVVM pattern just flunked my test on productivity and has just turned into a big yucky hack! The clear case in point is adding support for a Modal dialog box. The correct way is to put up a dialog box and tie it to a view model. Getting this to work is difficult. In order to benefit from the MVVM pattern, you have to distribute code in several places throughout the layers of your application. You also have to use esoteric programming constructs like templates and lamba expressions. Stuff that makes you stare at the screen scratching your head. This makes maintenance and debugging a nightmare waiting to happen as I recently discovered. I had an about box working fine until I got an exception the second time I invoked it, saying that it couldn’t show the dialog box again once it is closed. I had to add an event handler for the close functionality to the dialog window, another one in the IDialogView implementation of it and finally another in the IDialogViewModel. I thought MVVM would save us from such extravagant hackery! There are several folks out there with competing solutions to this problem and they are all hacks and don’t provide a clean, easily reusable, elegant solution. Most of the MVVM toolkits gloss over dialogs and when they do address them, they are just alert boxes that don’t require custom interfaces or view models. I’m planning on giving up on the MVVM view pattern, at least its orthodox implementation of it. What do you think? Has it been worth the trouble for you if you had any? Am I just a incompetent programmer or does MVVM not what it's hyped up to be?

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• Semi-complex aggregate select statement confusion

  - by Ian Henry

  Alright, this problem is a little complicated, so bear with me. I have a table full of data. One of the table columns is an EntryDate. There can be multiple entries per day. However, I want to select all rows that are the latest entry on their respective days, and I want to select all the columns of said table. One of the columns is a unique identifier column, but it is not the primary key (I have no idea why it's there; this is a pretty old system). For purposes of demonstration, say the table looks like this: create table ExampleTable ( ID int identity(1,1) not null, PersonID int not null, StoreID int not null, Data1 int not null, Data2 int not null, EntryDate datetime not null ) The primary key is on PersonID and StoreID, which logically defines uniqueness. Now, like I said, I want to select all the rows that are the latest entries on that particular day (for each Person-Store combination). This is pretty easy: --Figure 1 select PersonID, StoreID, max(EntryDate) from ExampleTable group by PersonID, StoreID, dbo.dayof(EntryDate) Where dbo.dayof() is a simple function that strips the time component from a datetime. However, doing this loses the rest of the columns! I can't simply include the other columns, because then I'd have to group by them, which would produce the wrong results (especially since ID is unique). I have found a dirty hack that will do what I want, but there must be a better way -- here's my current solution: select cast(null as int) as ID, PersonID, StoreID, cast(null as int) as Data1, cast(null as int) as Data2, max(EntryDate) as EntryDate into #StagingTable from ExampleTable group by PersonID, StoreID, dbo.dayof(EntryDate) update Target set ID = Source.ID, Data1 = Source.Data1, Data2 = Source.Data2, from #StagingTable as Target inner join ExampleTable as Source on Source.PersonID = Target.PersonID and Source.StoreID = Target.StoreID and Source.EntryDate = Target.EntryDate This gets me the correct data in #StagingTable but, well, look at it! Creating a table with null values, then doing an update to get the values back -- surely there's a better way to do this? A single statement that will get me all the values the first time? It is my belief that the correct join on that original select (Figure 1) would do the trick, like a self-join or something... but how do you do that with the group by clause? I cannot find the right syntax to make the query execute. I am pretty new with SQL, so it's likely that I'm missing something obvious. Any suggestions? (Working in T-SQL, if it makes any difference)

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• Unity framework - creating & disposing Entity Framework datacontexts at the appropriate time

  - by TobyEvans

  Hi there, With some kindly help from StackOverflow, I've got Unity Framework to create my chained dependencies, including an Entity Framework datacontext object: using (IUnityContainer container = new UnityContainer()) { container.RegisterType<IMeterView, Meter>(); container.RegisterType<IUnitOfWork, CommunergySQLiteEntities>(new ContainerControlledLifetimeManager()); container.RegisterType<IRepositoryFactory, SQLiteRepositoryFactory>(); container.RegisterType<IRepositoryFactory, WCFRepositoryFactory>("Uploader"); container.Configure<InjectedMembers>() .ConfigureInjectionFor<CommunergySQLiteEntities>( new InjectionConstructor(connectionString)); MeterPresenter meterPresenter = container.Resolve<MeterPresenter>(); this works really well in creating my Presenter object and displaying the related view, I'm really pleased. However, the problem I'm running into now is over the timing of the creation and disposal of the Entity Framework object (and I suspect this will go for any IDisposable object). Using Unity like this, the SQL EF object "CommunergySQLiteEntities" is created straight away, as I've added it to the constructor of the MeterPresenter public MeterPresenter(IMeterView view, IUnitOfWork unitOfWork, IRepositoryFactory cacheRepository) { this.mView = view; this.unitOfWork = unitOfWork; this.cacheRepository = cacheRepository; this.Initialize(); } I felt a bit uneasy about this at the time, as I don't want to be holding open a database connection, but I couldn't see any other way using the Unity dependency injection. Sure enough, when I actually try to use the datacontext, I get this error: ((System.Data.Objects.ObjectContext)(unitOfWork)).Connection '((System.Data.Objects.ObjectContext)(unitOfWork)).Connection' threw an exception of type 'System.ObjectDisposedException' System.Data.Common.DbConnection {System.ObjectDisposedException} My understanding of the principle of IoC is that you set up all your dependencies at the top, resolve your object and away you go. However, in this case, some of the child objects, eg the datacontext, don't need to be initialised at the time the parent Presenter object is created (as you would by passing them in the constructor), but the Presenter does need to know about what type to use for IUnitOfWork when it wants to talk to the database. Ideally, I want something like this inside my resolved Presenter: using(IUnitOfWork unitOfWork = new NewInstanceInjectedUnitOfWorkType()) { //do unitOfWork stuff } so the Presenter knows what IUnitOfWork implementation to use to create and dispose of straight away, preferably from the original RegisterType call. Do I have to put another Unity container inside my Presenter, at the risk of creating a new dependency? This is probably really obvious to a IoC guru, but I'd really appreciate a pointer in the right direction thanks Toby

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• Lawler's Algorithm Implementation Assistance

  - by Richard Knop

  Here is my implemenation of Lawler's algorithm in PHP (I know... but I'm used to it): <?php $jobs = array(1, 2, 3, 4, 5, 6); $jobsSubset = array(2, 5, 6); $n = count($jobs); $processingTimes = array(2, 3, 4, 3, 2, 1); $dueDates = array(3, 15, 9, 7, 11, 20); $optimalSchedule = array(); foreach ($jobs as $j) { $optimalSchedule[] = 0; } $dicreasedCardinality = array(); for ($i = $n; $i >= 1; $i--) { $x = 0; $max = 0; // loop through all jobs for ($j = 0; $j < $i; $j++) { // ignore if $j already is in the $dicreasedCardinality array if (false === in_array($j, $dicreasedCardinality)) { // if the job has no succesor in $jobsSubset if (false === isset($jobs[$j+1]) || false === in_array($jobs[$j+1], $jobsSubset)) { // here I find an array index of a job with the maximum due date // amongst jobs with no sucessor in $jobsSubset if ($x < $dueDates[$j]) { $x = $dueDates[$j]; $max = $j; } } } } // move the job at the end of $optimalSchedule $optimalSchedule[$i-1] = $jobs[$max]; // decrease the cardinality of $jobs $dicreasedCardinality[] = $max; } print_r($optimalSchedule); Now the above returns an optimal schedule like this: Array ( [0] => 1 [1] => 1 [2] => 1 [3] => 3 [4] => 2 [5] => 6 ) Which doesn't seem right to me. The problem might be with my implementation of the algorithm because I am not sure I understand it correctly. I used this source to implement it: http://www.google.com/books?id=aSiBs6PDm9AC&pg=PA166&dq=lawler%27s+algorithm+code&lr=&hl=sk&cd=4#v=onepage&q=&f=false The description there is a little confusing. For example, I didn't quite get how is the subset D defined (I guess it is arbitrary). Could anyone help me out with this? I have been trying to find some sources with simpler explanation of the algorithm but all sources I found were even more complicated (with math proofs and such) so I am stuck with the link above. Yes, this is a homework, if it wasn't obvious. I still have few weeks to crack this but I have spent few days already trying to get how exactly this algorithm works with no success so I don't think I will get any brighter during that time.

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• How to GET a read-only vs editable resource in REST style?

  - by Val

  I'm fairly familiar with REST principles, and have read the relevant dissertation, Wikipedia entry, a bunch of blog posts and StackOverflow questions on the subject, but still haven't found a straightforward answer to a common case: I need to request a resource to display. Depending on the resource's state, I need to render either a read-only or an editable representation. In both cases, I need to GET the resource. How do I construct a URL to get the read-only or editable version? If my user follows a link to GET /resource/<id>, that should suffice to indicate to me that s/he needs the read-only representation. But if I need to server up an editable form, what does that URL look like? GET /resource/<id>/edit is obvious, but it contains a verb in the URL. Changing that to GET /resource/<id>/editable solves that problem, but at a seemingly superficial level. Is that all there is to it -- change verbs to adjectives? If instead I use POST to retrieve the editable version, then how do I distinguish between the POST that initially retrieves it, vs the POST that saves it? My (weak) excuse for using POST would be that retrieving an editable version would cause a change of state on the server: locking the resource. But that only holds if my requirements are to implement such a lock, which is not always the case. PUT fails for the same reason, plus PUT is not enabled by default on the Web servers I'm running, so there are practical reasons not to use it (and DELETE). Note that even in the editable state, I haven't made any changes yet; presumably when I submit the resource to the Web server again, I'd POST it. But to get something that I can later POST, the server has to first serve up a particular representation. I guess another approach would be to have separate resources at the collection level: GET /read-only/resource/<id> and GET /editable/resource/<id> or GET /resource/read-only/<id> and GET /resource/editable/<id> ... but that looks pretty ugly to me. Thoughts?

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• CSS Background-Images Loading after HTML Images (Involves Javascript)

  - by Kevin C.

  I threw together a quick little microsite that you can see at http://monterraauction.com. If you don't have a super-fast connection (and nothing's cached), the very last items to load are the background-images that are used for CSS image-text replacement (primarily, that h1#head at the top, with a 7kb background image). Nothing debilitating, but it looks slightly awkward. And I'm asking this question as a matter of curiosity more than anything else ;) Also, please note that this occurs in Firefox, but not Chrome. Now, underneath the h1#head I have a jquery.cycle.lite-powered slideshow in div#photo. In the HTML markup there are a total of 13, heavy image files that make up each of the slides. If I remove all but the first slide, then the problem goes away! So the CSS background-images are loading after...those HTML images are done? But here's what's confusing: I check it out in YSlow...the CSS background-images have a much lower response time than all of the slides in #photo. Right after all the JS files finish loading, in fact. So why aren't they showing up first? I tried $('#photo img:last-child').load(function() { alert('Locked and Loaded!')});, but the background-images pop up a while before the alert does, so I'm assuming it's not waiting until the last slide has loaded (admittedly I'm a bit of JS noob so maybe I'm just making a wrong assumption). I also tried commenting out all the jquery.cycle.lite stuff, so that I knew I didn't have any JS manipulating the DOM elements in #photo, but that wasn't the problem. I tried putting all the JS at the bottom of the document, right before </body>, but that didn't work. Lastly, I tried turning off javascript, and of course the css background-image loads way before the images in #photo, so it's definitely a JS thing (amirite?) I guess the obvious solution here is to mark the slides up as LINKS rather than IMGs, and have Javascript insert those 12 extra slideshow images after the DOM is ready--users without javascript shouldn't need to download the extra images anyways. But again, I'm curious: Why does removing the extra HTML images from within #photo solve the problem? And why are the CSS background-images showing up after the HTML images have loaded, even though YSlow says the css background-images loaded first? Seeing as how it happens in FF but not Chrome, is it simply a browser issue? I appreciate any insight you guys could give me!

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• iPhone app with tab bar and navigation bar as peers

  - by Mac

  I'm trying to write an application that uses a navigation bar and tab bar in what (I'm gathering) is an unusual manner. Basically, I've got several "pages" ("home", "settings", etc) that each have their own tab. I'd also like to have it so that the "home" page is the root view of the navigation bar, and the other pages are the second-level views of the navigation bar. That is, I should be able to navigate to any page by clicking the appropriate tab bar item, and should be able to navigate to the home page from any other page by clicking the navigation bar's back button. Currently, I have a UINavigationBar (through a UINavigationController) and a UITabBar (through a UITabController) as children of a UIView. The various pages' view controllers are set as the tab controller's viewControllers property, and the home page's controller is also set as the navigation controller's root view. Each page view's tag is set to its index in the tab control. I have the following logic in the tab controller's didSelectViewController delegate method: - (void) tabBarController:(UITabBarController*) tabBarController didSelectViewController:(UIViewController*) viewController { if ([navController.viewControllers count] > 1) [navController popViewControllerAnimated:NO]; [navController pushViewController:viewController animated:YES]; } Also, in the navigation controller's didShowViewController delegate method, I have the following code: - (void) navigationController:(UINavigationController *) navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated { tabController.selectedIndex = viewController.view.tag; } The problem that's occurring is that when I run this, the navigation bar, tab bar and home page all display ok, but the tab bar will not respond to input - I cannot select a different tab. I gather it's more usual to have the tab bar as the child of the navigation control, or vice versa. This doesn't seem to fit my approach, because I don't want to have to individually create the subordinate control each time a change occurs in the parent control - eg: recreate tab bar each time the navigation bar changes. Does anyone have suggestions as to what's wrong and how to fix it? I'm probably missing something obvious, but whatever it is I can't seem to find it. Thanks! EDIT: I'm guessing it has something to do with both controller's trying to have ownership of the page controller, but I can't for the life of me figure out a way around it.

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• How do I use .htaccess RewriteRule to change underscores to dashes

  - by soopadoubled

  I'm working on a site, and its CMS used to save new page urls using the underscore character as a word seperator. Despite the fact that Google now treats underscore as a word seperator, the SEO powers that be are demanding the site use dashes instead. This is very easy to do within the CMS, and I can of course change all existing URLs saved in the MySQL database that serves the CMS. My problem lies in writing a .htaccess rule that will 301 old style underscore seperated links to the new style hyphenated verstion. I had success using the answers to this Stack Overflow question on other sites, using: RewriteRule ^([^_]*)_([^_]*_.*) $1-$2 [N] RewriteRule ^([^_]*)_([^_]*)$ /$1-$2 [L,R=301] However this CMS site uses a lot of existing rules to produce clean URLs, and I can't get this working in conjunction with the existing rule set. .htaccess currently looks like this: Options FollowSymLinks # RewriteOptions MaxRedirects=50 RewriteEngine On RewriteBase / RewriteCond %{HTTP_HOST} !^www\.mydomain\.co\.uk$ [NC] RewriteRule (.*) http://www.mydomain.co.uk/$1 [R=301,L] #trailing slash enforcement RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_URI} !# RewriteCond %{REQUEST_URI} !(.*)/$ RewriteRule ^(.*)$ http://www.mydomain.co.uk/$1/ [L,R=301] RewriteRule ^test/([0-9]+)(/)?$ test_htaccess.php?year=$1 [nc] RewriteRule ^index(/)?$ index.php RewriteRule ^department/([^/]*)/([^/]*)/([^/]*)(/)?$ ecom/index.php?action=ecom.details&mode=$1&$2=$3 [nc] RewriteRule ^department/([^/]*)(/)?$ ecom/index.php?action=ecom.details&mode=$1 [nc] RewriteRule ^product/([^/]*)/([^/]*)/([^/]*)(/)?$ ecom/index.php?action=ecom.pdetails&mode=$1&$2=$3 [nc] RewriteRule ^product/([^/]*)(/)?$ ecom/index.php?action=ecom.pdetails&mode=$1 [nc] RewriteRule ^content/([^/]*)(/)?$ ecom/index.php?action=ecom.cdetails&mode=$1 [nc] RewriteRule ([^/]*)/action/([^/]*)/([^/]*)/([^/]*)/([^/]*)(/)?$ $1/index.php?action=$2&mode=$3&$4=$5 [nc] RewriteRule ([^/]*)/action/([^/]*)/([^/]*)(/)?$ $1/index.php?action=$2&mode=$3 [nc] RewriteRule ([^/]*)/action/([^/]*)(/)?$ $1/index.php?action=$2 [nc] RewriteRule ^eaction/([^/]*)/([^/]*)/([^/]*)/([^/]*)(/)?$ ecom/index.php?action=$1&mode=$2&$3=$4 [nc] RewriteRule ^eaction/([^/]*)/([^/]*)(/)?$ ecom/index.php?action=$1&mode=$2 [nc] RewriteRule ^action/([^/]*)/([^/]*)(/)?$ index.php?action=$1&mode=$2 [nc] RewriteRule ^sid/([^/]*)(/)?$ index.php?sid=$1 [nc] ## Error Handling ## #RewriteRule ^error/([^/]*)(/)?$ index.php?action=error&mode=$1 [nc] # ----------------------------------- Content Section ------------------------------ # #RewriteRule ^([^/]*)(/)?$ index.php?action=cms&mode=$1 [nc] RewriteRule ^accessibility(/)?$ index.php?action=cms&mode=accessibility RewriteRule ^terms(/)?$ index.php?action=cms&mode=conditions RewriteRule ^privacy(/)?$ index.php?action=cms&mode=privacy RewriteRule ^memberpoints(/)?$ index.php?action=cms&mode=member_points RewriteRule ^contactus(/)?$ index.php?action=contactus RewriteRule ^sitemap(/)?$ index.php?action=sitemap ErrorDocument 404 /index.php?action=error&mode=content ExpiresDefault "access plus 3 days" All page URLS are in one of the 3 following formats: http://www.mydomain.com/department/some_page_address/ http://www.mydomain.com/product/some_page_address/ http://www.mydomain.com/content/some_page_address/ I'm sure I am missing something obvious, but at this level my regex and mod_rewrite skills clearly aren't up to par. Any ideas would be greatly appreciated!

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• Most efficient algorithm for merging sorted IEnumerable<T>

  - by franck

  Hello, I have several huge sorted enumerable sequences that I want to merge. Theses lists are manipulated as IEnumerable but are already sorted. Since input lists are sorted, it should be possible to merge them in one trip, without re-sorting anything. I would like to keep the defered execution behavior. I tried to write a naive algorithm which do that (see below). However, it looks pretty ugly and I'm sure it can be optimized. It may exist a more academical algorithm... IEnumerable<T> MergeOrderedLists<T, TOrder>(IEnumerable<IEnumerable<T>> orderedlists, Func<T, TOrder> orderBy) { var enumerators = orderedlists.ToDictionary(l => l.GetEnumerator(), l => default(T)); IEnumerator<T> tag = null; var firstRun = true; while (true) { var toRemove = new List<IEnumerator<T>>(); var toAdd = new List<KeyValuePair<IEnumerator<T>, T>>(); foreach (var pair in enumerators.Where(pair => firstRun || tag == pair.Key)) { if (pair.Key.MoveNext()) toAdd.Add(pair); else toRemove.Add(pair.Key); } foreach (var enumerator in toRemove) enumerators.Remove(enumerator); foreach (var pair in toAdd) enumerators[pair.Key] = pair.Key.Current; if (enumerators.Count == 0) yield break; var min = enumerators.OrderBy(t => orderBy(t.Value)).FirstOrDefault(); tag = min.Key; yield return min.Value; firstRun = false; } } The method can be used like that: // Person lists are already sorted by age MergeOrderedLists(orderedList, p => p.Age); assuming the following Person class exists somewhere: public class Person { public int Age { get; set; } } Duplicates should be conserved, we don't care about their order in the new sequence. Do you see any obvious optimization I could use?

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• What's the best way to structure this Linq-to-Events Drag & Drop code?

  - by Rob Fonseca-Ensor

  I am trying to handle a drag & drop interaction, which involves mouse down, mouse move, and mouse up. Here is a simplified repro of my solution that: on mouse down, creates an ellipse and adds it to a canvas on mouse move, repositions the ellipse to follow the mouse on mouse up, changes the colour of the canvas so that it's obvious which one you're dragging. var mouseDown = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonDown"); var mouseUp = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonUp"); var mouseMove = Observable.FromEvent<MouseEventArgs>(canvas, "MouseMove"); Ellipse ellipse = null; var q = from start in mouseDown.Do(x => { // handle mousedown by creating a red ellipse, // adding it to the canvas at the right position ellipse = new Ellipse() { Width = 10, Height = 10, Fill = Brushes.Red }; Point position = x.EventArgs.GetPosition(canvas); Canvas.SetLeft(ellipse, position.X); Canvas.SetTop(ellipse, position.Y); canvas.Children.Add(ellipse); }) from delta in mouseMove.Until(mouseUp.Do(x => { // handle mouse up by making the ellipse green ellipse.Fill = Brushes.Green; })) select delta; q.Subscribe(x => { // handle mouse move by repositioning ellipse Point position = x.EventArgs.GetPosition(canvas); Canvas.SetLeft(ellipse, position.X); Canvas.SetTop(ellipse, position.Y); }); the XAML is simply <Canvas x:Name="canvas"/> There's a few things I don't like about this code, and I need help refactoring it :) First of all: the mousedown and mouseup callbacks are specified as side effects. If two subscriptions are made to q, they will happen twice. Second, the mouseup callback is specified before the mousemove callback. This makes it a bit hard to read. Thirdly, the reference to the ellipse seems to be in a silly place. If there's two subscriptions, that variable reference will get overwritten quite quickly. I'm sure that there should be some way we can leverage the let keyword to introduce a variable to the linq expression that will mean the correct ellipse reference is available to both the mouse move and mouse up handlers How would you write this code?

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• From a 3D modeler to an iPhone app - what are best practices?

  - by bonkey

  I am quite new in 3D programming on iPhone and I would like to ask for hints about organizing a work between designers and programmers on that platform. Most of all: what kind of tools, libraries or plugins cooperate the best on both sides. Although I consider the question as looking for general best-practices advice I would like to find a solution for my current situation which I describe further, too. I've already done some research and found following libraries: SIO2 Khronos OpenGL ES 1.x SDK for PowerVR MBX Unity3D Oolong Game Engine I've checked modellers or plugins to them giving output formats readable by those tools: obj2opengl Wavefront OBJ to plain header file converter Blender with SIO2 exporter iphonewavefrontloader Cheetah3D PVRGeoPOD for 3DS / Maya Unfortunately I still have no clear vision how to combine any of that tools to get a desinger's work in an application. I look for a way of getting it in the most possible complete way: models, lights, scenes, textures, maybe some simple animations (but rather no game-like physics), but I still got nothing. And here comes my situation: I would like to find right way to present few (but quite complicated) models from a single scene. The designers mostly use 3DS Max 9, sometimes 10 (which partly prevents using PVRGeoPOD) and are rather reluctant to switch to something else but if there's no other choice I suppose it would be possible. The basic rule I've already found in some places "use Wavefront OBJ" not always works. I haven't got any acceptable results with production files, actually. The only things worked fine were some mere examples. Some of my models did imported incomplete, sometimes exporters hung or generated enormous files not really useful on an iPhone, sometimes enabling textures (with GL_TEXTURE_2D) just crashed an app. I know it might be a problem with too complicated models or my mistakes coming from inexeperience but I am not able to find any guidelines for that process to have streamlined cooperation with designers. I am even willing to write some things from scratch in pure OpenGL-ES if it's necessary, but I would like to avoid what might be avoided and get the most from the model files. The best would be the effect I saw on some SIO2 tutorials: export, build & go. But at that moment I've got only "import, wrong", "import, where are textures?", "import, that almost looks fine, export, hang" and so on... Is it really so much frustrating or I am just missed something obvious? Can anybody share his/her experience in that field and tell what kind of software uses for "making things happen"?

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• Is this asking too much of a browser?

  - by Matt Ball

  I'm embedding a large array in <script> tags in my HTML, like this (nothing surprising): <script> var largeArray = [/* lots of stuff in here */]; </script> In this particular example, the array has 210,000 elements. That's well below the theoretical maximum of 231 - by 4 orders of magnitude. Here's the fun part: if I save JS source for the array to a file, that file is 44 megabytes (46,573,399 bytes, to be exact). If you want to see for yourself, you can download it from my Dropbox. (All the data in there is canned, so much of it is repeated. This will not be the case in production.) Now, I'm really not concerned about serving that much data. My server gzips its responses, so it really doesn't take all that long to get the data over the wire. However, there is a really nasty tendency for the page, once loaded, to crash the browser. I'm not testing at all in IE (this is an internal tool). My primary targets are Chrome 8 and Firefox 3.6. In Firefox, I can see a reasonably useful error in the console: Error: script stack space quota is exhausted In Chrome, I simply get the sad-tab page: Cut to the chase, already Is this really too much data for our modern, "high-performance" browsers to handle? Is there anything I can do* to gracefully handle this much data? Incidentally, I was able to get this to work (read: not crash the tab) on-and-off in Chrome. I really thought that Chrome, at least, was made of tougher stuff, but apparently I was wrong... Edit 1 @Crayon: I wasn't looking to justify why I'd like to dump this much data into the browser at once. Short version: either I solve this one (admittedly not-that-easy) problem, or I have to solve a whole slew of other problems. I'm opting for the simpler approach for now. @various: right now, I'm not especially looking for ways to actually reduce the number of elements in the array. I know I could implement Ajax paging or what-have-you, but that introduces its own set of problems for me in other regards. @Phrogz: each element looks something like this: {dateTime:new Date(1296176400000), terminalId:'terminal999', 'General___BuildVersion':'10.05a_V110119_Beta', 'SSM___ExtId':26680, 'MD_CDMA_NETLOADER_NO_BCAST___Valid':'false', 'MD_CDMA_NETLOADER_NO_BCAST___PngAttempt':0} @Will: but I have a computer with a 4-core processor, 6 gigabytes of RAM, over half a terabyte of disk space ...and I'm not even asking for the browser to do this quickly - I'm just asking for it to work at all! ? *other than the obvious: sending less data to the browser

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