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• How would i go about showing the closest paragraph element to a unique link with jQuery?

  - by Nike

  The title is a bit rusty, sorry about that. Now let me explain what i'm trying to do. I have a few listed items, like this: <li> <a id="toggle" class="0"><h4>ämne<small>2010-04-17 kl 12:54</small></h4></a> <p id="meddel" class="0">text</p> </li> <li class='odd'> <a id="toggle" class="1"><h4>test<small>2010-04-17 kl 15:01</small></h4></a> <p id="meddel" class="1">test meddelande :) [a]http://youtube.com[/a]</p> </li> The function i'm trying to achieve, is that when a user clicks a "toggle" link (the h4 text), i want the paragraph element below it to fade in. I thought of the idea of giving both the toggle link and the paragraph the same class, and then somehow make it get the paragraph with the same class as the toggle link clicked, and show it? But i'm not entirely sure how to do that either, and tbh, it doesn't sound like the greatest idea, but maybe that's the only way? I don't know... Is there some way to just simply get the nearest paragraph (below the link) with the id "meddel" and fade it in? That sounds a bit easier... I hope you can at least give me a few hints. Thanks in advance, -Nike

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• Core principles, rules, and habits for CS students

  - by Asad Butt

  No doubt there is a lot to read on blogs, in books, and on Stack Overflow, but can we identify some guidelines for CS students to use while studying? For me these are: Finish your course books early and read 4-5 times more material relative to your course work. Programming is the one of the fastest evolving professions. Follow the blogs on a daily basis for the latest updates, news, and technologies. Instead of relying on assignments and exams, do at least one extra, non-graded, small to medium-sized project for every programming course. Fight hard for internships or work placements even if they are unpaid, since 3 months of work 1 year at college. Practice everything, every possible and impossible way. Try doing every bit of your assignments project yourself; i.e. fight for every inch. Rely on documentation as the first source for help and samples, Google, and online forums as the last source. Participate often in online communities and forums to learn the best possible approach for every solution to your problem. (After doing your bit.) Make testing one of your habits as it is getting more important everyday in programming. Make writing one of your habits. Write something productive once or twice a week and publish it.

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• Is it OK to use WPF assemblies in a web app?

  - by Chris

  I have an ASP.NET MVC 2 app targeting .NET 4 that needs to be able to resize images on the fly and write them to the response. I have code that does this and it works. I am using System.Drawing.dll. However, I want to enhance my code so that not only am I resizing the image, but I am dropping it from 24bpp down to 4bit grayscale. I could not, for the life of me, find code on how to do this with System.Drawing.dll. But I did find a bunch of WPF stuff. This is my working/sample code (runs in LinqPad). // Load the original 24 bit image var bitmapImage = new BitmapImage(); bitmapImage.BeginInit(); bitmapImage.UriSource = new Uri(@"C:\Temp\Resized\18_appa2_015.png", UriKind.Absolute); //bitmapImage.DecodePixelWidth = 600; bitmapImage.EndInit(); // Create the destination image var formatConvertedBitmap = new FormatConvertedBitmap(); formatConvertedBitmap.BeginInit(); formatConvertedBitmap.Source = bitmapImage; formatConvertedBitmap.DestinationFormat = PixelFormats.Gray4; formatConvertedBitmap.EndInit(); // Encode and dump the image to disk var encoder = new PngBitmapEncoder(); encoder.Frames.Add(BitmapFrame.Create(formatConvertedBitmap)); using (var fileStream = File.Create(@"C:\Temp\Resized\18_appa2_015_s2.png")) { encoder.Save(fileStream); } It uses System.Xaml.dll, WindowsBase.dll, PresentationCore.dll, and PresentationFramework.dll. The namespaces used are: System.Windows.Controls, System.Windows.Media, and System.Windows.Media.Imaging. Is there any problem using these namespaces in my web application? It doesn't seem right. If anyone knows how to drop the bit depth without all this WPF stuff (which I barely understand, BTW) I would be thrilled to see that too.

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• Looking for a fast, compact, streamable, multi-language, strongly typed serialization format

  - by sanity

  I'm currently using JSON (compressed via gzip) in my Java project, in which I need to store a large number of objects (hundreds of millions) on disk. I have one JSON object per line, and disallow linebreaks within the JSON object. This way I can stream the data off disk line-by-line without having to read the entire file at once. It turns out that parsing the JSON code (using http://www.json.org/java/) is a bigger overhead than either pulling the raw data off disk, or decompressing it (which I do on the fly). Ideally what I'd like is a strongly-typed serialization format, where I can specify "this object field is a list of strings" (for example), and because the system knows what to expect, it can deserialize it quickly. I can also specify the format just by giving someone else its "type". It would also need to be cross-platform. I use Java, but work with people using PHP, Python, and other languages. So, to recap, it should be: Strongly typed Streamable (ie. read a file bit by bit without having to load it all into RAM at once) Cross platform (including Java and PHP) Fast Free (as in speech) Any pointers?

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• Collision detections and how efficient they are

  - by Shadow

  How exactly do you implement collision detection? What are the costs involved? Do different platforms(c/c++, java, cocoa/iphone, flash, directX) have different optimizations for calculating collisions. And lastly are there libraries available to do this for me, or some that I can just interpret for my platform of choice? As I understand it you would need to loop through the collision map and find the area in question and then compair the input thing(e.g. a sprite) to the type of pixel that is in the questioned area. I understand the very basic idea, but I don't understand the underlying implementation or even a higher level one for that matter. It would seem that this type of detection, or any for that matter, is very costly. Tile map? Bit array? How are these created from an image(I would guess looping and doing stuff)? The reason I ask this question is to get a better understanding of the efficiency behind the scenes and to understand exactly what is going on. Links, references, or examples would be very helpful. I know this question is a bit longwinded so any help or references would be very welcome. Thanks SO!

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• Help a Beginner with a PHP based Login System

  - by Brian Lang

  I'm a bit embarrassed to say, but I've run into issue with creating a PHP based login system. I'm using a site template to handle the looks of the the login process, so I will spare you the code. Here is my thought process on how to handle the login: Create a simple login.php file. On there will be a form whose action is set to itself. It will check to see if the submit has been clicked, and if so validate to make sure the user entered a valid password / username. If they do, set a session variable save some login info (username, NOT password), and redirect them to a restricted area. If the login info isn't valid, save an error message in a session variable, display error message giving further instruction, and wait for the user to resubmit. Here is a chunk of what I have - hopefully one of you experts can see where I've gone wrong, and give me some insight: if(isset($_POST['submit'])) { if(!empty($_POST['username']) AND !empty(!$_POST['password'])) { header("Location: http://www.google.com"); } else { $err = 'All the fields must be filled in!'; } } if($err) { $_SESSION['msg']['login-err'] = $err; } ? Now the above is just an example - the intent of the above code is to process user input, with the script validating simply that the user has given input for username and password. If they have, I would like them, in this case, to be redirected to google.com (for the sake of this example). If not, save an error message. Given my current code, the error message will display perfectly, however if the user submits and has something entered for the username and password, the page simply doesn't redirect. I'm sure this is a silly question, but I am a beginner, and well, to be honest, a bit buzzed right now. Thanks so much!

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• Module not found

  - by TMP

  Hi There! I've been working on this one quite a bit and haven't gotten any closer to a solution. I juut dug up my old copy of the WindowsHookLib again - It's available with source at http://www.codeproject.com/KB/DLL/WindowsHookLib.aspx. This library allows Global Windows Mouse/Keyboard/Clipboard Hooks, which is very useful. I'm trying to use the Mouse Hook in here to Capture Mouse-Motion (I could use a Timer that always polls Cursor.Position, but I plan on using more features of WindowsHookLib later). Code as follows: MouseHook mh = new MouseHook(); mh.InstallHook(); mh.MouseMove += new EventHandler<WindowsHookLib.MouseEventArgs>(mh_MouseMove); But on the call to InstallHook(), I get an Exception: "The specified Module could not be found". Strange. Searching, I found that someone thought this occurs because a DLL is not in a place included in the Windows PATH variable, and because placing it in system32 didn't help I went the whole hog and translated the thing to C# for inclusion directly in my project (I was curious how it works). However the error was obstinately persistent, so I dug a bit on this, and found the Code in the Library that is responsible: In InstallHook(), we have IntPtr hinstDLL = Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]); this._hMouseHook = UnsafeNativeMethods.SetWindowsHookEx(14, this._mouseProc, hinstDLL, 0); if (this._hMouseHook == IntPtr.Zero) { throw new MouseHookException(new Win32Exception(Marshal.GetLastWin32Error()).Message); } And this (after modification and recompile) tells me that what I'm really getting is a Windows error "ERROR_MOD_NOT_FOUND"! Now, Here I'm stumped. Didn't I just compile the Hook Library directly into my project? (UnsafeMethods.SetWindowsHookEx is just a DllImported Method from user32) Any Answers, or Prods in the right direction, or any hints, pointers or similar are very much appreciated!

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• Truly declarative language?

  - by gjvdkamp

  Hi all, Does anyone know of a truly declarative language? The behaviour I'm looking for is kind of what Excel does, where I can define variables and formulas, and have the formula's result change when the input changes (without having set the answer again myself) The behaviour I'm looking for is best shown with this pseudo code: X = 10 // define and assign two variables Y = 20; Z = X + Y // declare a formula that uses these two variables X = 50 // change one of the input variables ?Z // asking for Z should now give 70 (50 + 20) I've tried this in a lot of languages like F#, python, matlab etc, but every time i try this they come up with 30 instead of 70. Wich is correct from an imperative point of view, but i'm looking for a more declerative behaviour if you know what i mean. And this is just a very simple calculation. When things get more difficult it should handle stuff like recursion and memoization automagically. The code below would obviously work in C# but it's just so much code for the job, i'm looking for something a bit more to the point without all that 'technical noise' class BlaBla{ public int X {get;set;} // this used to be even worse before 3.0 public int Y {get;set;} public int Z {get{return X + Y;}} } static void main(){ BlaBla bla = new BlaBla(); bla.X = 10; bla.Y = 20; // can't define anything here bla.X = 50; // bit pointless here but I'll do it anyway. Console.Writeline(bla.Z);// 70, hurray! } This just seems like so much code, curly braces and semicolons that add nothing. Is there a language/ application (apart from Exel) that does this? Maybe I'm no doing it right in the mentioned langauges, or I've completely missed an app that does just this. I prototyped a language/ application that does this (along with some other stuff) and am thinking of productizing it. I just can't believe it's not there yet. Don't want to waste my time. Thanks in advance, Gert-Jan

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• Getting Depth Value on Kinect SDK 1.6

  - by AlexanderPD

  this is my first try on Kinect and Kinect SDK so I'm having a lot of "newbie issues" :) my goal is to point my mouse on the Kinect standard video output and get the depth value. I already have both normal video and depth video outputs by using the 2 "Color Basic-WPF" and "Depth Basic-WPF" samples, and handling mouse events or position is not a problem. In fact i already did all and i already got a depth value, but this value is always HIGHLY imprecise. It jumps from 500 to 4000 by just moving to the next pixel in a plane surface. So.. I'm pretty sure I'm reading the depth value in the wrong way. This is how i read it: short debugValue = depthPixels[x*y].Depth; debug.Text = "X = "+x+", Y = "+y+", value = "+debugValue.ToString(); i know it's pretty out of context, this little piece of code is inside the same SensorDepthFrameReady function in "Depth Basic-WPF"! "x" and "y" are the mouse coordinates and depthPixels is DepthImagePixel[] type, a temporary array filled with the "depthFrame.CopyDepthImagePixelDataTo(this.depthPixels);" instruction. Depth frame is filled here: DepthImageFrame depthFrame = e.OpenDepthImageFrame() the "e" comes from here: private void SensorDepthFrameReady(object sender, DepthImageFrameReadyEventArgs e) and this last one is called here: this.sensor.DepthFrameReady += this.SensorDepthFrameReady; how i must handle that depth value i get? I know the value must be between 800 and 4000 but i get values between about 500 and about 8000. i already google a lot (here on SO too) and i still can't understand if the depth value is 11 or 13 bit. The sdk examples uses shrink this value to 8 bit and this is making even more confusion in my head :(

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• CSS: how come html, body height: 100% is more then 100% ?!

  - by Nati

  hey, i was trying to do a bottom sticky footer link test and but it kept being more then 100% meaning it scrolled a litle bit.. so i made a simple HTML code, without any additions but its still more than 100%, see here: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="he" lang="he" dir="rtl" id="bangler"> <head> <title>my title</title> <style type="text/css"> html, body, #wrapper { height: 100%; } body > #wrapper { height: auto; min-height: 100%; } </style> </head> <body> <div id="wrapper">aa</div> </body> </html> the thing is, it scrolls just a little bit more then 100% meaning about 5-10px more.. this is really strange, on both IE and Firefox !! Thanks in advance !

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• OpenGL pixels drawn with each horizontal pair swapped

  - by Tim Kane

  I'm somewhat new to OpenGL though I'm fairly sure my problem lies in the pixel format being used, or how my texture is being generated... I'm drawing a texture onto a flat 2D quad using a 16bit RGB5_A1 pixel format, though I don't make use of any alpha at this stage. The problem I'm having is that each pair of horizontal pixel values have been swapped. That is... if the pixels positions should be in this order (assume 8x2 image) 0 1 2 3 4 5 6 7 they are instead drawn as 1 0 3 2 5 4 7 6 Or, more clearly from this image (below). Left is what I get... Right is what I should get. . The question is... How have I ended up with this? Is there something wrong with the pixel format? Unlikely since the colours all appear correct, and I would expect all kinds of nasty if it were down to endian-ness. Suggestions greatly appreciated. Update: Turns out the problem was in my source renderer. Interestingly, I've avoided the problem entirely by using 32-bit textures (haven't tried 24-bit at this point).

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• Wrong colors when merging images with PHP

  - by OfficeJet

  Hi, I want to get images ID's and creat from files a merged image according to the given ID's. This code is called by ajax and return the image file name (which is the server time to prevent browser caching). code: if (isset($_REQUEST['items'])){ $req_items = $_REQUEST['items']; } else { $req_items = 'a'; } $items = explode(',',$req_items); $bg_img = imagecreatefrompng('bg.png'); for ($i=0; $i<count($items); $i++){ $main_img = $items[$i].'-large.png'; $image = imagecreatefrompng($main_img); $image_tc = imagecreatetruecolor(300, 200); imagecopy($image_tc,$image,0,0,0,0,300,200); $black = imagecolorallocate($image_tc, 0, 0, 0); imagecolortransparent($image_tc, $black); $opacity = 100; $bg_width = 300; $bg_height = 200; $dest_x = 0;//$image_size[0] - $bg_width - $padding; $dest_y = 0;//$image_size[1] - $bg_height - $padding; imagecopymerge($bg_img, $image_tc, $dest_x, $dest_y, 0, 0, $bg_width, $bg_height, $opacity) ; } $file = $_SERVER['REQUEST_TIME'].'.jpg'; imagejpeg($bg_img, $file, 100); echo $file; imagedestroy($bg_img); imagedestroy($image); die(); The images are shown exactly as I want but with wrong colors. I lately added the part with imagecreatetruecolor and imagecolortransparent, and still got wrong results. I also saved the PNG itself on a 24 bit format and also later as 8 bit - not helping. every ideas is very welcomed ! Thanks

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• Is there really such a thing as a char or short in modern programming?

  - by Dean P

  Howdy all, I've been learning to program for a Mac over the past few months (I have experience in other languages). Obviously that has meant learning the Objective C language and thus the plainer C it is predicated on. So I have stumbles on this quote, which refers to the C/C++ language in general, not just the Mac platform. With C and C++ prefer use of int over char and short. The main reason behind this is that C and C++ perform arithmetic operations and parameter passing at integer level, If you have an integer value that can fit in a byte, you should still consider using an int to hold the number. If you use a char, the compiler will first convert the values into integer, perform the operations and then convert back the result to char. So my question, is this the case in the Mac Desktop and IPhone OS environments? I understand when talking about theses environments we're actually talking about 3-4 different architectures (PPC, i386, Arm and the A4 Arm variant) so there may not be a single answer. Nevertheless does the general principle hold that in modern 32 bit / 64 bit systems using 1-2 byte variables that don't align with the machine's natural 4 byte words doesn't provide much of the efficiency we may expect. For instance, a plain old C-Array of 100,000 chars is smaller than the same 100,000 ints by a factor of four, but if during an enumeration, reading out each index involves a cast/boxing/unboxing of sorts, will we see overall lower 'performance' despite the saved memory overhead?

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• Loading a helper elsewhere than the autoload.php?

  - by drpcken

  I inherited a project and I'm cleaning up a bit and trying to finish it. I noticed that they used (or wrote) a breadcrumb helper. It is in my helpers folder and is named breadcrumb_helper.php It has a single function to build a breadcrumb menu with links and pass it to the view breadcrumbs.php. Here's the code: function show_breadcrumbs() { $ci =& get_instance(); $ci->load->helper('inflector'); $data = ''; //build breadcrumb and store in $data $this->load->view("breadcrumbs", $data) } I was trying to figure out how this helper worked and I checked the autoload.php but there is no reference to the helper in there. In face here is my autoload: $autoload['helper'] = array('url','asset','combine','navigation','form','portfolio','cookie','default'); This show_breadcrumbs() function is used quite a bit in some of my pages so I'm confused as to how its loading if it isn't in the autoloader. It is called like this in a few of my pages: <?=show_breadcrumbs()?> What am I missing? Why isn't this in my autoload? I even did a global search and couldn't find anywhere the helper is being loaded.

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• Rails Tableless Model

  - by mplacona

  I'm creating a tableless Rails model, and am a bit stuck on how I should use it. Basically I'm trying to create a little application using Feedzirra that scans a RSS feed every X seconds, and then sends me an email with only the updates. I'm actually trying to use it as an activerecord model, and although I can get it to work, it doesn't seem to "hold" data as expected. As an example, I have an initializer method that parses the feed for the first time. On the next requests, I would like to simply call the get_updates method, which according to feedzirra, is the existing object (created during the initialize) that gets updated with only the differences. I'm finding it really hard to understand how this all works, as the object created on the initialize method doesn't seem to persist across all the methods on the model. My code looks something like: def initialize feed parse here end def get_updates feedzirra update passing the feed object here end Not sure if this is the right way of doing it, but it all seems a bit confusing and not very clear. I could be over or under-doing here, but I'd like your opinion about this approach. Thanks in advance

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• C# : Forcing a clean run in a long running SQL reader loop?

  - by Wardy

  I have a SQL data reader that reads 2 columns from a sql db table. once it has done its bit it then starts again selecting another 2 columns. I would pull the whole lot in one go but that presents a whole other set of challenges. My problem is that the table contains a large amount of data (some 3 million rows or so) which makes working with the entire set a bit of a problem. I'm trying to validate the field values so i'm pulling the ID column then one of the other cols and running each value in the column through a validation pipeline where the results are stored in another database. My problem is that when the reader hits the end of handlin one column I need to force it to immediately clean up every little block of ram used as this process uses about 700MB and it has about 200 columns to go through. Without a full Garbage Collect I will definately run out of ram. Anyone got any ideas how I can do this? I'm using lots of small reusable objects, my thought was that I could just call GC.Collect() on the end of each read cycle and that would flush everything out, unfortunately that isn't happening for some reason.

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• Visual Studio crashes consistently on web-related projects

  - by Traveling Tech Guy

  Hi, I have a brand new VS2010 installed on a Win2008R2 machine. I started getting this error when debugging a WCF service project: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt." When I started developing a web site a week later, this became consistent - I can't debug it. The stack dump reads: at Microsoft.VisualStudio.WebHost.Host.ProcessRequest(Connection conn) at Microsoft.VisualStudio.WebHost.Server.OnSocketAccept(Object acceptedSocket) at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback() I tried searching online, and some recommend turning off the "Suppress JIT Optimizations" in the Debugging options - this dos not seem to make a difference. Clearly the problem is with the built in web server. But am I doing something wrong? Is there something I can do? Or is this a known bug? Thanks for your time, Guy Update 12/31: Today I tried using CassiniDev as a replacement to the original VS2010 WebServer - exact same result. My suspicion is that there's some internal conflict between VS2010, Windows Server 2008R2 and maybe the fact that it's a 64 bit OS. I switched to using IIS as my debug server - and that seems to work, with some annoying side effects. My conclusion: do not use a 64 bit server system as your dev machine. Develop on 32bit - deploy to 64bit. Side conclusion: there are some scenarios Microsoft's QA doesn't test.

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• MSBuild / PowerShell: Copy SQL Server 2012 database to SQL Azure via BACPAC (for Continuous Integration)

  - by giveme5minutes

  I'm creating a continuous integration MSBuild script which copies a database in on-premise SQL Server 2012 to SQL Azure. Easy right? Methods After a fair bit of research I've come across the following methods: Use PowerShell to access the DAC library directly, then use the MSBuild PowerShell extension to wrap the script. This would require installing PowerShell 3 and working out how to make the MSBuild PowerShell extension work with it, as apparently MS moved the DAC API to a different namespace in the latest version of the library. PowerShell would give direct access to the API, but may require quite a bit of boilerplate. Use the sample DAC Framework Client Side Tools, which requires compiling them myself, as the downloads available from Codeplex only include the Hosted version. It would also require fixing them to use DAC 3.0 classes as they appear to currently use an earlier version of DAC. I could then call these tools from an <Exec Command="" /> in the MSBuild script. Less boilerplate and if I hit any bumps in the road I can just make changes to the source. Processes Using whichever method, the process could be either: Export from on-premise SQL Server 2012 to local BACPAC Upload BACPAC to blog storage Import BACPAC to SQL Azure via Hosted DAC Or: Export from on-premise SQL Server 2012 to local BACPAC Import BACPAC to SQL Azure via Client DAC Question All of the above seems to be quite a lot of effort for something that seems to be a standard feature... so before I start reinventing the wheel and documenting the results for all to see, is there something really obvious that I've missed here? Is there pre-written script that MS has released that I have not yet uncovered? There's an command in the GUI of SQL Server Management Studio 2012 that does EXACTLY what I'm trying to do (right click on local database, click "Tasks", click "Deploy Database to SQL Azure"). Surely if it's a few clicks in the GUI it must be a single command on the command line somewhere??

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• How can I run Ruby specs and/or tests in MacVim without locking up MacVim?

  - by Henry

  About 6 months ago I switched from TextMate to MacVim for all of my development work, which primarily consists of coding in Ruby, Ruby on Rails and JavaScript. With TextMate, whenever I needed to run a spec or a test, I could just command+R on the test or spec file and another window would open and the results would be displayed with the 'pretty' format applied. If the spec or test was a lengthy one, I could just continue working with the codebase since the test/spec was running in a separate process/window. After the test ran, I could click through the results directly to the corresponding line in the spec file. Tim Pope's excellent rails.vim plugin comes very close to emulating this behavior within the MacVim environment. Running :Rake when the current buffer is a test or spec runs the file then splits the buffer to display the results. You can navigate through the results and key through to the corresponding spot in the file. The problem with the rails.vim approach is that it locks up the MacVim window while the test runs. This can be an issue with big apps that might have a lot of setup/teardown built into the tests. Also, the visual red/green html results that TextMate displays (via --format pretty, I'm assuming) is a bit easier to scan than the split window. This guy came close about 18 mos ago: http://cassiomarques.wordpress.com/2009/01/09/running-rspec-files-from-vim-showing-the-results-in-firefox/ The script he has worked with a bit of hacking, but the tests still ran within MacVim and locked up the current window. Any ideas on how to fully replicate the TextMate behavior described above in MacVim? Thanks!

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• .Net lambda expression-- where did this parameter come from?

  - by larryq

  I'm a lambda newbie, so if I'm missing vital information in my description please tell me. I'll keep the example as simple as possible. I'm going over someone else's code and they have one class inheriting from another. Here's the derived class first, along with the lambda expression I'm having trouble understanding: class SampleViewModel : ViewModelBase { private ICustomerStorage storage = ModelFactory<ICustomerStorage>.Create(); public ICustomer CurrentCustomer { get { return (ICustomer)GetValue(CurrentCustomerProperty); } set { SetValue(CurrentCustomerProperty, value); } } private int quantitySaved; public int QuantitySaved { get { return quantitySaved; } set { if (quantitySaved != value) { quantitySaved = value; NotifyPropertyChanged(p => QuantitySaved); //where does 'p' come from? } } } public static readonly DependencyProperty CurrentCustomerProperty; static SampleViewModel() { CurrentCustomerProperty = DependencyProperty.Register("CurrentCustomer", typeof(ICustomer), typeof(SampleViewModel), new UIPropertyMetadata(ModelFactory<ICustomer>.Create())); } //more method definitions follow.. Note the call to NotifyPropertyChanged(p => QuantitySaved) bit above. I don't understand where the "p" is coming from. Here's the base class: public abstract class ViewModelBase : DependencyObject, INotifyPropertyChanged, IXtremeMvvmViewModel { public event PropertyChangedEventHandler PropertyChanged; protected virtual void NotifyPropertyChanged<T>(Expression<Func<ViewModelBase, T>> property) { MvvmHelper.NotifyPropertyChanged(property, PropertyChanged); } } There's a lot in there that's not germane to the question I'm sure, but I wanted to err on the side of inclusiveness. The problem is, I don't understand where the 'p' parameter is coming from, and how the compiler knows to (evidently?) fill in a type value of ViewModelBase from thin air? For fun I changed the code from 'p' to 'this', since SampleViewModel inherits from ViewModelBase, but I was met with a series of compiler errors, the first one of which statedInvalid expression term '=>' This confused me a bit since I thought that would work. Can anyone explain what's happening here?

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• How should developers cope with so many GUI configuration combinations?

  - by shawn-harrison

  These days, any decent Windows desktop application must perform well and look good under the following conditions: XP and Vista and Windows 7. 32 bit and 64 bit. With and without Themes. With and without Aero. At 96 and 120 and perhaps custom DPIs. One or more monitors (screens). Each OS has its own preferred font. Oh my! What is a lowly little Windows desktop application developer to do? :( I'm hoping to get a thread started with suggestions on how to deal with this GUI dilemma. First off, I'm on Delphi 7. a) Does Delphi 2010 bring anything new to the table to help with this situation? b) Should we pick an aftermarket component suite and rely on them to solve all these problems? c) Should we go with an aftermarket skinning engine? d) Perhaps a more HTML-type GUI is the way to go. Can we make a relatively complex GUI app with HTML that doesn't require using a browser? (prefer to keep it form based) e) Should we just knuckle down and code through each one of these scenarios and quit bitching about it? f) And finally, how in the world are we supposed to test all these conditions?

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• Connecting an overloaded PyQT signal using new-style syntax

  - by Claudio

  I am designing a custom widget which is basically a QGroupBox holding a configurable number of QCheckBox buttons, where each one of them should control a particular bit in a bitmask represented by a QBitArray. In order to do that, I added the QCheckBox instances to a QButtonGroup, with each button given an integer ID: def populate(self, num_bits, parent = None): """ Adds check boxes to the GroupBox according to the bitmask size """ self.bitArray.resize(num_bits) layout = QHBoxLayout() for i in range(num_bits): cb = QCheckBox() cb.setText(QString.number(i)) self.buttonGroup.addButton(cb, i) layout.addWidget(cb) self.setLayout(layout) Then, each time a user would click on a checkbox contained in self.buttonGroup, I'd like self.bitArray to be notified so I can set/unset the corresponding bit in the array. For that I intended to connect QButtonGroup's buttonClicked(int) signal to QBitArray's toggleBit(int) method and, to be as pythonic as possible, I wanted to use new-style signals syntax, so I tried this: self.buttonGroup.buttonClicked.connect(self.bitArray.toggleBit) The problem is that buttonClicked is an overloaded signal, so there is also the buttonClicked(QAbstractButton*) signature. In fact, when the program is executing I get this error when I click a check box: The debugged program raised the exception unhandled TypeError "QBitArray.toggleBit(int): argument 1 has unexpected type 'QCheckBox'" which clearly shows the toggleBit method received the buttonClicked(QAbstractButton*) signal instead of the buttonClicked(int) one. So, the question is, how can we specify, using new-style syntax, that self.buttonGroup emits the buttonClicked(int) signal instead of the default overload - buttonClicked(QAbstractButton*)?

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• How can I emulate Vim's * search in GNU Emacs?

  - by rq

  In Vim the * key in normal mode searches for the word under the cursor. In GNU Emacs the closest native equivalent would be: C-s C-w But that isn't quite the same. It opens up the incremental search mini buffer and copies from the cursor in the current buffer to the end of the word. In Vim you'd search for the whole word, even if you are in the middle of the word when you press *. I've cooked up a bit of elisp to do something similar: (defun find-word-under-cursor (arg) (interactive "p") (if (looking-at "\\<") () (re-search-backward "\\<" (point-min))) (isearch-forward)) That trots backwards to the start of the word before firing up isearch. I've bound it to C-+, which is easy to type on my keyboard and similar to *, so when I type C-+ C-w it copies from the start of the word to the search mini-buffer. However, this still isn't perfect. Ideally it would regexp search for "\<" word "\>" to not show partial matches (searching for the word "bar" shouldn't match "foobar", just "bar" on its own). I tried using search-forward-regexp and concat'ing \ but this doesn't wrap in the file, doesn't highlight matches and is generally pretty lame. An isearch-* function seems the best bet, but these don't behave well when scripted. Any ideas? Can anyone offer any improvements to the bit of elisp? Or is there some other way that I've overlooked?

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• Basic question on retain/release semantics from Apple's reference library

  - by davetron5000

  I have done Objective-C way back when, and have recently (i.e. just now) read the documentation on Apple's site regarding the use of retain and release. However, there is a bit of code in their Creating an iPhone Application page that has me a bit confused: - (void)setUpPlacardView { // Create the placard view -- it calculates its own frame based on its image. PlacardView *aPlacardView = [[PlacardView alloc] init]; self.placardView = aPlacardView; [aPlacardView release]; // What effect does this have on self.placardView?! placardView.center = self.center; [self addSubview:placardView]; } Not seeing the entire class, it seems that self.placardView is also a PlacardView * and the assignment of it to aPlacardView doesn't seem to indicate it will retain a reference to it. So, it appears to me that the line I've commented ([aPlacardView release];) could result in aPlacardView having a retain count of 0 and thus being deallocated. Since self.placardView points to it, wouldn't that now point at deallocated memory and cause a problem?

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• Implicit Type Conversions in Reflection

  - by bradhe

  So I've written a quick bit of code to help quickly convert between business objects and view models. Not to pimp my own blog, but you can find the details here if you're interested or need to know. One issue I've run in to is that I have a custom collection type, ProductCollection, and I need to turn that in to a string[] in on my model. Obviously, since there is no default implicit cast, I'm getting an exception in my contract converter. So, I thought I would write the next little bit of code and that should solve the problem: public static implicit operator string[](ProductCollection collection) { var list = new List<string>(); foreach (var product in collection) { if (product.Id == null) { list.Add(null); } else { list.Add(product.Id.ToString()); } } return list.ToArray(); } However, it still fails with the same cast exception. I'm wondering if it has something to do with being in reflection? If so, is there anything that I can do here?? I'm open to architectural solutions, too!

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