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• World's Most Challening MySQL SQL Query (least I think so...)

  - by keruilin

  Whoever answers this question can claim credit for solving the world's most challenging SQL query, according to yours truly. Working with 3 tables: users, badges, awards. Relationships: user has many awards; award belongs to user; badge has many awards; award belongs to badge. So badge_id and user_id are foreign keys in the awards table. The business logic at work here is that every time a user wins a badge, he/she receives it as an award. A user can be awarded the same badge multiple times. Each badge is assigned a designated point value (point_value is a field in the badges table). For example, BadgeA can be worth 500 Points, BadgeB 1000 Points, and so on. As further example, let's say UserX won BadgeA 10 times and BadgeB 5 times. BadgeA being worth 500 Points, and BadgeB being worth 1000 Points, UserX has accumulated a total of 10,000 Points ((10 x 500) + (5 x 1000)). The end game here is to return a list of top 50 users who have accumulated the most badge points. Can you do it?

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• What does this structure actually do?

  - by LGTrader

  I found this structure code in a Julia Set example from a book on CUDA. I'm a newbie C programmer and cannot get my head around what it's doing, nor have I found the right thing to read on the web to clear it up. Here's the structure: struct cuComplex { float r; float i; cuComplex( float a, float b ) : r(a), i(b) {} float magnitude2( void ) { return r * r + i * i; } cuComplex operator*(const cuComplex& a) { return cuComplex(r*a.r - i*a.i, i*a.r + r*a.i); } cuComplex operator+(const cuComplex& a) { return cuComplex(r+a.r, i+a.i); } }; and it's called very simply like this: cuComplex c(-0.8, 0.156); cuComplex a(jx, jy); int i = 0; for (i=0; i<200; i++) { a = a * a + c; if (a.magnitude2() > 1000) return 0; } return 1; So, the code did what? Defined something of structure type 'cuComplex' giving the real and imaginary parts of a number. (-0.8 & 0.156) What is getting returned? (Or placed in the structure?) How do I work through the logic of the operator stuff in the struct to understand what is actually calculated and held there? I think that it's probably doing recursive calls back into the stucture float magnitude2 (void) { return return r * r + i * i; } probably calls the '*' operator for r and again for i, and then the results of those two operations call the '+' operator? Is this correct and what gets returned at each step? Just plain confused. Thanks!

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• WPF/MVVM - keep ViewModels in application component or separate?

  - by Anders Juul

  Hi all, I have a WPF application where I'm using the MVVM pattern. I get the VM activated for actions that require user input and thus need to activate views from the VM. I've started out separating the VMs into a separate component/assembly, partly because I see them as the unit testable part, partly because views should rely on VM, not the other way round. But when I then need to bring up a window, the window is not known by the VM. All introductions I find place the VM in the WPF/App component, thus eliminating the problem. This article recommends keeping them in separate layers : http://waf.codeplex.com/wikipage?title=Architecture%20-%20Get%20The%20Big%20Picture&referringTitle=Home As I see it, I have the following choices Move VMs to the WPF/App assembly to allow VMs to access the windows directly. Place interfaces of views in VM-assembly, implement views in WPF/App assembly and register the connection through IOC or alternative ways. File a 'request' from the VM into some mechanism/bus that routes the request (but which mechanism!? E.g something in Prism?!) What's the recommendation? Thanks for any comments, Anders, Denmark

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• Most cost effective way to target multiple mobile platforms

  - by niidto

  Hi I have been given the tasks of speccing a mobile application, which will need to run on approx. 1000 devices. These devices already exist, and consist of iPhones, BlackBerrys, Androids, Windows Mobile and Netbooks. The application will have simple reporting capability, and a collection of forms. Anyway, the obvious solution would be to develop some browser based solution, although given the occasionally connected nature of the devices, there's a potential for data to get lost / not saved. So instead of creating a complex application for each platform, I was thinking we could build what is effectively a form generator, with basic offline storage capability (text files), designed to run on each device, and have the device generate a form, based on for example an XML file that it could request from a server somewhere, resulting in minimal specialist development costs, and the ability to run most of the logic from the server end, with the devices being dumb clients that render forms and upload the data when there is an available connection. Anyway, my question summarised is, how have you made the decision on supporting multiple devices for your application. Is this always an unavoidable problem, and you just have to make the call to support 1 or 2, or pay for developers to write code for each platform, or alternatively supply pre-installed devices to the company? Many thanks James

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• ASP.NET MVC editor template for property

  - by Idsa

  Usually I render my forms by @Html.RenderModel, but this time I have a complex rendering logic and I render it manually. I decided to create a editor template for one property. Here is the code (copy pasted from default object editor template implementation): <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %> <% var modelMetadata = ViewData.ModelMetadata; %> <% if (modelMetadata.HideSurroundingHtml) { %> <%= Html.Editor(modelMetadata.PropertyName) %> <% } else { %> <% if (!String.IsNullOrEmpty(Html.Label(modelMetadata.PropertyName).ToHtmlString())) { %> <div class="editor-label"><%= Html.Label(modelMetadata.PropertyName) %></div> <% } %> <div class="editor-field"> <%= Html.Editor(modelMetadata.PropertyName) %> <%= Html.ValidationMessage(modelMetadata.PropertyName) %> </div> <% } %> And here is how I use it: @Html.EditorFor(x => x.SomeProperty, "Property") //"Property" is template above But it didn't work: labels are rendered regardless of DisplayName and editors are not rendered at all (in Watches Html.Editor(modelMetadata.PropertyName shows empty string). What am I doing wrong?

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• php paging class

  - by Stick it to THE MAN

  Can anyone recommend a good PHP paging class? I have searched google, but have not seen anything that matches my requirements. Rather than "rolling my own" (and almost surely reinventing the wheel), I decided to check in here first. First some background: I am developing a website using Symfony 1.3.2 with Propel ORM on Ubuntu 9.10. I am currently using the Propel pager, which is OK, but I recently started using memcache to speed things up a little. At this point, the Propel pager is of little use, as it (AFAIK), only works with Propel objects. What I need is a class th:t meets the following requirents Has clean interface, with separation of concerns, so that the logic to retrieve records from the datasource (e.g. database) is encapsulated in a class (or at least a separate file). Can work with arrays of objects Provides pagination links, and only fetches the data required for the current page. Also, the pagination should 'split' the available page links if there are too many. For example, if there are potentially 1000 possible page links, the pages displayed should be something like FIRST 2,3 ....999 LAST Can return the number of all the records in the table being queried, so that the following links are available FIRST, LAST (this requirement is actually already covered in the previous requirement - but I just wanted to re-emphasise it). Can anyone recommend such a library, if they have used it succesfully in the past? Alternatively, someobe may have 'hacked' (e.g. derived from) the current Propel pager, to get it to do the things I listed about - please let me know.

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• [Delphi] How would you refactor this code?

  - by Al C

  This hypothetical example illustrates several problems I can't seem to get past, even though I keep trying!! ... Suppose the original code is a long event handler, coded in the UI, triggered when a user clicks a cell in a grid. Expressed as pseudocode it's: if Condition1=true then begin //loop through every cell in row, //if aCell/headerCellValue>1 then //color aCell red end else if Condition2=true then begin //do some other calculation adding cell and headerCell values, and //if some other product>2 then //color the whole row green end else show an error message I look at this and say "Ah, refactor to the strategy pattern! The code will be easier to understand, easier to debug, and easier to later extend!" I get that. And I can easily break the code into multiple procedures. The problem is ultimately scope related. Assume the pseudocode makes extensive use of grid properties, values displayed in cells, maybe even built-in grid methods. How do you move all that to another unit, without referencing the grid component in the UI--which would break all the "rules" about loose coupling that make OOP valuable? ... I'm really looking forward to responses. Thanks, as always -- Al C.

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• How do I use price data in one table for a calculation that is stored in another table?

  - by shane

  I'm still leanring PHP/MySQL but have learned quite a bit thanks to codies on StackOverflow. I'm trying to setup a sort of room reservations system using two tables: SETUP: Room price table: Has, prices for a type room a client may want to rent as well as the dates (day of week) they wish to use it. Pricing varies based on day of the week and per room. I've setup a different table for each room type as each room type carries different pricing for each day of the week. So, There is an Alpha room table, Bravo room, etc. Within Alpha table are headers for the days of the week with pricing pre-entered into the rows. Client info table: Has the name, address, date of room use, etc data for the specific client. EXAMPLE: Alpha-room price table: Sun = $100; Mon = $200; Tue=$300 and so on. Bravo-room price table: Sun = $100; Mon = $200; Tue=$300 and so on. Client data table: ClientName; date-of-room-use; address; day_subtotal; grand_total. QUESTION: I'm trying to find PHP code that will: look at the date of room use in the client data table, look up the associated cost for that date in the specific room pricing table, record that unit cost in the day subtotal of the client data table and sum a grand total in the grand total row of the client data table (assuming the room may be used more than one day by the customer). I know there's something to do with join but I'm finding it difficult to grasp the concept and, if someone can demonstrate using this example, I think I will have a better understanding of how to work this sort of transaction. Thank you ALL in advance for your suggestions or alternatvie approaches.

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• How to handle not-enough-isolatedstorage issue deep in data loader?

  - by Edward Tanguay

  I have a silverlight application which loads data from many external data sources into IsolatedStorage, and while loading any of these sources if it does not have enough IsolatedStorage, it ends up in a catch statement. At that point in that catch statement I would like to ask the user to click a button to approve silverlight to increase the IsolatedStorage capacity. The problem is, although I have a "SwitchPage()" method with which I display a page, if I access it at this point it is too deep in the loading process and the application always goes into an endless loop, hangs and crashes. I need a way to branch out of the application completely somehow to an independent UserControl which has a button and code behind which does the increase logic. What is a solution for an application to be able to branch out of a loading process catch statement like this, display a user control which has a button to ask the user to increase the IsolatedStorage? public static void SaveBitmapImageToIsolatedStorageFile(OpenReadCompletedEventArgs e, string fileName) { try { using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication()) { using (IsolatedStorageFileStream isfs = new IsolatedStorageFileStream(fileName, FileMode.Create, isf)) { Int64 imgLen = (Int64)e.Result.Length; byte[] b = new byte[imgLen]; e.Result.Read(b, 0, b.Length); isfs.Write(b, 0, b.Length); isfs.Flush(); isfs.Close(); isf.Dispose(); } } } catch (IsolatedStorageException) { //handle: present user with button to increase isolated storage } catch (TargetInvocationException) { //handle: not saved } }

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• Perl - CodeGolf - Nested loops & SQL inserts

  - by CheeseConQueso

  I had to make a really small and simple script that would fill a table with string values according to these criteria: 2 characters long 1st character is always numeric (0-9) 2nd character is (0-9) but also includes "X" Values need to be inserted into a table on a database The program would execute: insert into table (code) values ('01'); insert into table (code) values ('02'); insert into table (code) values ('03'); insert into table (code) values ('04'); insert into table (code) values ('05'); insert into table (code) values ('06'); insert into table (code) values ('07'); insert into table (code) values ('08'); insert into table (code) values ('09'); insert into table (code) values ('0X'); And so on, until the total 110 values were inserted. My code (just to accomplish it, not to minimize and make efficient) was: use strict; use DBI; my ($db1,$sql,$sth,%dbattr); %dbattr=(ChopBlanks => 1,RaiseError => 0); $db1=DBI->connect('DBI:mysql:','','',\%dbattr); my @code; for(0..9) { $code[0]=$_; for(0..9) { $code[1]=$_; insert(@code); } insert($code[0],"X"); } sub insert { my $skip=0; foreach(@_) { if($skip==0) { $sql="insert into table (code) values ('".$_[0].$_[1]."');"; $sth=$db1->prepare($sql); $sth->execute(); $skip++; } else { $skip--; } } } exit; I'm just interested to see a really succinct & precise version of this logic.

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• PHP Overloading, singleton instance

  - by jamalali81

  I've sort of created my own MVC framework and am curious as to how other frameworks can send properties from the "controller" to the "view". Zend does something along the lines of $this->view->name = 'value'; My code is: file: services_hosting.php class services_hosting extends controller { function __construct($sMvcName) { parent::__construct($sMvcName); $this->setViewSettings(); } public function setViewSettings() { $p = new property; $p->banner = '/path/to/banners/home.jpg'; } } file: controller.php class controller { public $sMvcName = "home"; function __construct($sMvcName) { if ($sMvcName) { $this->sMvcName = $sMvcName; } include('path/to/views/view.phtml'); } public function renderContent() { include('path/to/views/'.$this->sMvcName.'.phtml'); } } file: property.php class property { private $data = array(); protected static $_instance = null; public static function getInstance() { if (null === self::$_instance) { self::$_instance = new self(); } return self::$_instance; } public function __set($name, $value) { $this->data[$name] = $value; } public function __get($name) { if (array_key_exists($name, $this->data)) { return $this->data[$name]; } } public function __isset($name) { return isset($this->data[$name]); } public function __unset($name) { unset($this->data[$name]); } } In my services_hosting.phtml "view" file I have: <img src="<?php echo $this->p->banner ?>" /> This just does not work. Am I doing something fundamentally wrong or is my logic incorrect? I seem to be going round in circles at the moment. Any help would be very much appreciated.

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• Highlighting Manu Item : urlQuery

  - by phpExe

  I want to highlight menu item with url query. But in my function, all items will be "currentt". I think there is a logic bug in my function: function channel() { if (is_numeric($_GET['kanalID'])) { $kanalID = $_GET['kanalID']; } if ($_GET['kanalID'] == "") { $kanalID = 1;} $tv = array(1 => 'tv1', 3 => 'tv2', 7 => 'tv3', 8 => 'tv4', 25 => 'tv5', 26 => 'tv6', 39 => 'tv7', 41 => 'tv8'); $channel = '<ul class="channeList">'; foreach ($tv as $id => $kanal) { if($kanalID = $id){$class= "currentt";} $channel .= '<li> <a href="http://mysite.com/menu.php?kanalID='.$id.'" class="'.$class.'">'.$kanal.'</a> </li>'; } $channel .= '</ul>'; $channel .= '<div class="ply"><iframe src="http://mysite.com/index.php?id='.$kanalID.'&w=500&h=320" frameborder="0" width="500" height="320" ></iframe></div>'; return $channel; } echo channel(); How can I fix this? Thanks alot

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• Keeping dates in order when using date_select and discarding year in Rails?

  - by MikeH

  My app has users who have seasonal products. When a user selects a product, we allow him to also select the product's season. We accomplish this by letting him select a start date and an end date for each product. We're using date_select to generate two sets of drop-downs: one for the start date and one for the end date. Including years doesn't make sense for our model. So we're using the option: discard_year => true To explain our problem, consider that our products are apples. Vendor X carries apples every year from September to January. Years are irrelevant here, and that's why we're using discard_year => true. However, while the specific years are irrelevant, the relative point in time from the start date to the end date is relevant. This is where our problem arises. When you use discard_year => true, Rails does set a year in the database, it just doesn't appear in the views. Rails sets all the years to 0001 in our app. Going back to our apple example, this means that the database now thinks the user has selected September 0001 to January 0001. This is a problem for us for a number of reasons. To solve this, the logic that I need to implement is the following: - If season_start month/date is before season_end month/date, then standard Rails approach is fine. - But, if season_start month/date is AFTER season_end month/date, then I need to dynamically update the database field such that the year for season_end is equal to the year for season_start + 1. My best guess is that I would create a custom method that runs as an after_save or after_update in my products model. But I'm not really sure how to do this. Ideas? Anybody ever had this issue? Thanks!

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• Android NDK import-module / code reuse

  - by Graeme

  Morning! I've created a small NDK project which allows dynamic serialisation of objects between Java and C++ through JNI. The logic works like this: Bean - JavaCInterface.Java - JavaCInterface.cpp - JavaCInterface.java - Bean The problem is I want to use this functionality in other projects. I separated out the test code from the project and created a "Tester" project. The tester project sends a Java object through to C++ which then echo's it back to the Java layer. I thought linking would be pretty simple - ("Simple" in terms of NDK/JNI is usually a day of frustration) I added the JNIBridge project as a source project and including the following lines to Android.mk: NDK_MODULE_PATH=.../JNIBridge/jni/" JNIBridge/jni/JavaCInterface/Android.mk: ... include $(BUILD_STATIC_LIBRARY) JNITester/jni/Android.mk: ... include $(BUILD_SHARED_LIBRARY) $(call import-module, JavaCInterface) This all works fine. The C++ files which rely on headers from JavaCInterface module work fine. Also the Java classes can happily use interfaces from JNIBridge project. All the linking is happy. Unfortunately JavaCInterface.java which contains the native method calls cannot see the JNI method located in the static library. (Logically they are in the same project but both are imported into the project where you wish to use them through the above mechanism). My current solutions are are follows. I'm hoping someone can suggest something that will preserve the modular nature of what I'm trying to achieve: My current solution would be to include the JavaCInterface cpp files in the calling project like so: LOCAL_SRC_FILES := FunctionTable.cpp $(PATH_TO_SHARED_PROJECT)/JavaCInterface.cpp But I'd rather not do this as it would lead to me needing to update each depending project if I changed the JavaCInterface architecture. I could create a new set of JNI method signatures in each local project which then link to the imported modules. Again, this binds the implementations too tightly.

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• Application Design: Single vs. Multiple Hits to the DB

  - by shyneman

  I'm building a service that performs a set of configured activities based on the type of request that it receives. Each activity involves going to the database and retrieving/updating some kind of information. The logic for each activity can be generalized and re-used across different request types. The activities may need to participate in a transaction for the duration of the servicing the request. One option, I'm considering is having each activity maintain its own access to DAL/database. This fully encapsulates the activity into a stand-alone re-usable piece, but hitting the database multiple times for one request doesn't seem like a viable option. I don't really know how to easily implement the concept of a transaction across the multiple activities here either. The second option is to encapsulate ALL the activities into one big activity and hit the database once. But this does not allow re-use and configuration of these activities for different requests. Does anyone have any suggestions and input about what should be the best way to approach my problem? Thanks for any help.

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• Interchange structured data between Haskell and C

  - by Eonil

  First, I'm a Haskell beginner. I'm planning integrating Haskell into C for realtime game. Haskell does logic, C does rendering. To do this, I have to pass huge complexly structured data (game state) from/to each other for each tick (at least 30 times per second). So the passing data should be lightweight. This state data may laid on sequential space on memory. Both of Haskell and C parts should access every area of the states freely. In best case, the cost of passing data can be copying a pointer to a memory. In worst case, copying whole data with conversion. I'm reading Haskell's FFI(http://www.haskell.org/haskellwiki/FFICookBook#Working_with_structs) The Haskell code look specifying memory layout explicitly. I have a few questions. Can Haskell specify memory layout explicitly? (to be matched exactly with C struct) Is this real memory layout? Or any kind of conversion required? (performance penalty) If Q#2 is true, Any performance penalty when the memory layout specified explicitly? What's the syntax #{alignment foo}? Where can I find the document about this? If I want to pass huge data with best performance, how should I do that? *PS Explicit memory layout feature which I said is just C#'s [StructLayout] attribute. Which is specifying in-memory position and size explicitly. http://www.developerfusion.com/article/84519/mastering-structs-in-c/ I'm not sure Haskell has matching linguistic construct matching with fields of C struct.

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• How can this code throw a NullReferenceException?

  - by Davy8

  I must be going out of my mind, because my unit tests are failing because the following code is throwing a null ref exception: int pid = 0; if (parentCategory != null) { Console.WriteLine(parentCategory.Id); pid = parentCategory.Id; } The line that's throwing it is: pid = parentCategory.Id; The console.writeline is just to debug in the NUnit GUI, but that outputs a valid int. Edit: It's single-threaded so it can't be assigned to null from some other thread, and the fact the the Console.WriteLine successfully prints out the value shows that it shouldn't throw. Edit: Relevant snippets of the Category class: public class Category { private readonly int id; public Category(Category parent, int id) { Parent = parent; parent.PerformIfNotNull(() => parent.subcategories.AddIfNew(this)); Name = string.Empty; this.id = id; } public int Id { get { return id; } } } Well if anyone wants to look at the full code, it's on Google Code at http://code.google.com/p/chefbook/source/checkout I think I'm going to try rebooting the computer... I've seen pretty weird things fixed by a reboot. Will update after reboot. Update: Mystery solved. Looks like NUnit shows the error line as the last successfully executed statement... Copy/pasted test into new console app and ran in VS showed that it was the line after the if statement block (not shown) that contained a null ref. Thanks for all the ideas everyone. +1 to everyone that answered.

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• How do I push another viewController onto the navigationController from within a tabviewController?

  - by user207788

  Hi, I have a project set up using these two tutorials. http://twilloapp.blogspot.com/2009/03/how-to-embed-navigation-controller.html and the link for the second tutorial is at the bottom of the first. The tutorial is slightly outdated but I managed to get it to work as advertised. Now I want to push a new detailedView onto the NavigationController when a user touches a row in the table view. So I added this to my MyTableViewController.m file. - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { // Navigation logic may go here. Create and push another view controller. SecondViewController *detailViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController.xib" bundle:nil]; // ... // Pass the selected object to the new view controller. [self.navigationController pushViewController:detailViewController animated:YES]; [detailViewController release]; } Now when I run this project and touch a row in my table view I am getting an error: asm_Terminating_due_to_uncaught_exception IT seems to be having an issue loading the SecondViewController from nib, however I checked the detailViewController and it is not nil. I know I am missing something and it is more than likely something simple. Please help. Thanks, Bruce

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• C++ iterators, default initialization and what to use as an uninitialized sentinel.

  - by Hassan Syed

  The Context I have a custom template container class put together from a map and vector. The map resolves a string to an ordinal, and the vector resolves an ordinal (only an initial string to ordinal lookup is done, future references are to the vector) to the entry. The entries are modified intrusively to contain a a bool "assigned" and an iterator_type which is a const_iterator to the container class's map. My container class will use RCF's serialization code (which models boost::serialization) to serialize my container classes to nodes in a network. Serializing iterator's is not possible, or a can of worms, and I can easily regenerate them onces the vectors and maps are serialized on the remote site. The Question I need to default initialize, and be able to test that the iterator has not been assigned to (if it is assigned it is valid, if not it is invalid). Since map iterators are not invalidated upon operations performed on it (unless of course items are removed :D) am I to assume that map<x,y>::end() is a valid sentinel (regardless of the state of the map -- i.e., it could be empty) to initialize to ? I will always have access to the parent map, I'm just unsure wheather end() is the same as the map contents change. I don't want to use another level of indirection (--i.e., boost::optional) to achieve my goal, I'd rather forego compiler checks to correct logic, but it would be nice if I didn't need to. Misc This question exists, but most of its content seems non-sense. Assigning a NULL to an iterator is invalid according to g++ and clang++. This is another similar question, but it focuses on the common use-cases of iterators, which generally tends to be using the iterator to iterate, ofcourse in this use-case the state of the container isn't meant to change whilst iteration is going on.

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• How to find an embedded platform?

  - by gmagana

  I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction. Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do: Required: 2 RS232 serial ports (one used all the time for primary UI, the second one not continuous) 1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both] Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files) RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable. Nice to have: USB port(s) Ethernet network port Wireless network Implementation languages (any O/S I will adapt to): First choice Java/C# (Mono ok) Second choice is C/Pascal Third is BASIC Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size. Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-). EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

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• vectorizing loops in Matlab - performance issues

  - by Gacek

  This question is related to these two: http://stackoverflow.com/questions/2867901/introduction-to-vectorizing-in-matlab-any-good-tutorials http://stackoverflow.com/questions/2561617/filter-that-uses-elements-from-two-arrays-at-the-same-time Basing on the tutorials I read, I was trying to vectorize some procedure that takes really a lot of time. I've rewritten this: function B = bfltGray(A,w,sigma_r) dim = size(A); B = zeros(dim); for i = 1:dim(1) for j = 1:dim(2) % Extract local region. iMin = max(i-w,1); iMax = min(i+w,dim(1)); jMin = max(j-w,1); jMax = min(j+w,dim(2)); I = A(iMin:iMax,jMin:jMax); % Compute Gaussian intensity weights. F = exp(-0.5*(abs(I-A(i,j))/sigma_r).^2); B(i,j) = sum(F(:).*I(:))/sum(F(:)); end end into this: function B = rngVect(A, w, sigma) W = 2*w+1; I = padarray(A, [w,w],'symmetric'); I = im2col(I, [W,W]); H = exp(-0.5*(abs(I-repmat(A(:)', size(I,1),1))/sigma).^2); B = reshape(sum(H.*I,1)./sum(H,1), size(A, 1), []); But this version seems to be as slow as the first one, but in addition it uses a lot of memory and sometimes causes memory problems. I suppose I've made something wrong. Probably some logic mistake regarding vectorizing. Well, in fact I'm not surprised - this method creates really big matrices and probably the computations are proportionally longer. I have also tried to write it using nlfilter (similar to the second solution given by Jonas) but it seems to be hard since I use Matlab 6.5 (R13) (there are no sophisticated function handles available). So once again, I'm asking not for ready solution, but for some ideas that would help me to solve this in reasonable time. Maybe you will point me what I did wrong.

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• Work around for MessageNotReadableException in Java

  - by Hari

  Hi, I am building a small api around the JMS API for a project of mine. Essentially, we are building code that will handle the connection logic, and will simplify publishing messages by providing a method like Client.send(String message). One of the ideas being discussed right now is that we provide a means for the users to attach interceptors to this client. We will apply the interceptors after preparing the JMS message and before publishing it. For example, if we want to timestamp a message and wrote an interceptor for that, then this is how we would apply that ...some code ... Message message = session.createMessage() ..do all the current processing on the message and set the body for(interceptor:listOfInterceptors){ interceptor.apply(message) } One of the intrerceptors we though of was to compress the message body. But when we try to read the body of the message in the interceptor, we are getting a MessageNotReadableException. In the past, I normally compressed the content before setting it as the body of the message - so never had to worry about this exception. Is there any way of getting around this exception?

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• How deserealizing JSON with GSON

  - by loko

  I have one result of APPI http://developer.yahoo.com/geo/placefinder/guide/examples.html, I need to deserealizing the result JSON of example only with GSON http://where.yahooapis.com/geocode?location=San+Francisco,+CA&flags=J&appid=yourappid But i dont now have to do the class for deserealizing one JSON with array This is the reponse: {"ResultSet": {"version":"1.0", "Error":0, "ErrorMessage":"No error", "Locale":"en_US", "Quality":40, "Found":1, "Results":[ {"quality":40, "latitude":"37.779160", "longitude":"-122.420049", "offsetlat":"37.779160", "offsetlon":"-122.420049", "radius":5000, "name":"", "line1":"", "line2":"San Francisco, CA", "line3":"", "line4":"United States", "house":"", "street":"", "xstreet":"", "unittype":"", "unit":"", "postal":"", "neighborhood":"", "city":"San Francisco", "county":"San Francisco County", "state":"California", "country":"United States", "countrycode":"US", "statecode":"CA", "countycode":"", "uzip":"94102", "hash":"C1D313AD706E3B3C", "woeid":12587707, "woetype":9}] } } Im trying to deserealizing of this way but i couldn´t do that, please help me to do the correct class to get the JSON with GSON. public class LocationAddress { private ResultSet resultset; public static class ResultSet{ private String version; private String Error; private String ErrorMessage; private List<Results> results; } public static class Results{ private String quality; private String latitude; private String longitude; public String getQuality() { return quality; } public void setQuality(String quality) { this.quality = quality; } public String getLatitude() { return latitude; } public void setLatitude(String latitude) { this.latitude = latitude; } public String getLongitude() { return longitude; } public void setLongitude(String longitude) { this.longitude = longitude; } } }

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• Can I detect whether an object has called GC.SuppressFinalize?

  - by Joe White

  Is there a way to detect whether or not an object has called GC.SuppressFinalize? I have an object that looks something like this (full-blown Dispose pattern elided for clarity): public class ResourceWrapper { private readonly bool _ownsResource; private readonly UnmanagedResource _resource; public ResourceWrapper(UnmanagedResource resource, bool ownsResource) { _resource = resource; _ownsResource = ownsResource; if (!ownsResource) GC.SuppressFinalize(this); } ~ResourceWrapper() { if (_ownsResource) // clean up the unmanaged resource } } If the ownsResource constructor parameter is false, then the finalizer will have nothing to do -- so it seems reasonable (if a bit quirky) to call GC.SuppressFinalize right from the constructor. However, because this behavior is quirky, I'm very tempted to note it in an XML doc comment... and if I'm tempted to comment it, then I ought to write a unit test for it. But while System.GC has methods to set an object's finalizability (SuppressFinalize, ReRegisterForFinalize), I don't see any methods to get an object's finalizability. Is there any way to query whether GC.SuppressFinalize has been called on a given instance, short of buying Typemock or writing my own CLR host?

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• Recursion in prepared statements

  - by Rob

  I've been using PDO and preparing all my statements primarily for security reasons. However, I have a part of my code that does execute the same statement many times with different parameters, and I thought this would be where the prepared statements really shine. But they actually break the code... The basic logic of the code is this. function someFunction($something) { global $pdo; $array = array(); static $handle = null; if (!$handle) { $handle = $pdo->prepare("A STATEMENT WITH :a_param"); } $handle->bindValue(":a_param", $something); if ($handle->execute()) { while ($row = $handle->fetch()) { $array[] = someFunction($row['blah']); } } return $array; } It looked fine to me, but it was missing out a lot of rows. Eventually I realised that the statement handle was being changed (executed with different param), which means the call to fetch in the while loop will only ever work once, then the function calls itself again, and the result set is changed. So I am wondering what's the best way of using PDO prepared statements in a recursive way. One way could be to use fetchAll(), but it says in the manual that has a substantial overhead. The whole point of this is to make it more efficient. The other thing I could do is not reuse a static handle, and instead make a new one every time. I believe that since the query string is the same, internally the MySQL driver will be using a prepared statement anyway, so there is just the small overhead of creating a new handle on each recursive call. Personally I think that defeats the point. Or is there some way of rewriting this?

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