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• "Object reference not set to an instance of an object": why can't .NET show more details?

  - by Simon Chadwick

  "Object reference not set to an instance of an object" This is probably one of the most common run-time errors in .NET. Although the System.Exception has a stack trace, why does the exception not also show the name of the object reference field, or at least its type? Over the course of a year I spend hours sifting through stack traces (often in code I did not write), hoping there is a line number from a ".pdb" file, then finding the line in the code, and even then it is often not obvious which reference on the line was null. Having the name of the reference field would be very convenient. If System.ArgumentNullException instances can show the name of the method parameter ("Value cannot be null. Parameter name: value"), then surely System.NullReferenceException instances could include the name of the null field (or its containing collection).

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• SQLite INTERSECT gives a huge performance decrease

  - by Derk

  I have a query that runs in less than 1 ms: SELECT product_to_value.category AS category, features.name AS featurename, featurevalues.name AS valuename FROM product_to_value, features, featurevalues WHERE product_to_value.category IN(:int, :bla, :bla1) AND product_to_value.feature = features.int AND product_to_value.value = featurevalues.int LIMIT 10 However, when I combine it with another query using INTERSECT, the query now takes more than 250ms: SELECT product_to_value.category AS category, features.name AS featurename, featurevalues.name AS valuename FROM product_to_value, features, featurevalues WHERE product_to_value.category IN(:int, :bla, :bla1) AND product_to_value.feature = features.int AND product_to_value.value = featurevalues.int INTERSECT SELECT product_to_value.category AS category, features.name AS featurename, featurevalues.name AS valuename FROM product_to_value, features, featurevalues WHERE product_to_value.category IN(:int, :bla, :bla1) AND product_to_value.feature = features.int AND product_to_value.value = featurevalues.int LIMIT 10 This can't be right. I've tried several index combinations, for example an index on all columns I use in my query, but to no avail. I've tried compound indexes as well, but they only slow things down even more. I have read a few things about SQLite and how it treats indexes. I know SQLite is capable of delivering sick performance, and surely I must be overlooking something.

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• Enabling Direct3D-specific features (transparency AA)

  - by Bill Kotsias

  Hello. I am trying to enable transparency antialiasing in my Ogre-Direct3D application, but it just won't work. HRESULT hres = d3dSystem->getDevice()->SetRenderState(D3DRS_ADAPTIVETESS_Y, (D3DFORMAT)MAKEFOURCC('S', 'S', 'A', 'A')); /// returned value : hres == S_OK ! This method is taken from NVidia's technical report. I can enable transparency AA manually through the NVIDIA Control Panel, but surely I can't ask my users to do it like this. Anyone has any idea? Thank you for your time, Bill

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• How do I change apache2 DocumentRoot (default snow leopard install) and not get "You don't have perm

  - by David Peek

  I'm trying to point DocumentRoot at a directory in my user folder. While I can happily point DocumentRoot at /Library/WebServer/Documents and ~/Sites I keep getting "You don't have permission to access / on this server." when I point it anywhere else. OK, I just found a solution mid-question (stack overflow is just that good) by changing the user/group apache runs under to myuser/admin. I'm sure there must be a better way though. Surely some kind of permissions magic on the directory I'm pointing at?

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• Is DataGrid a necessity in WPF?

  - by Jobi Joy

  I have seen a lot of discussions going on and people asking about DataGrid for WPF and complaining about Microsoft for not having one with their WPF framework till date. We know that WPF is a great UI technology and have the Concept of ItemsControl,DataTemplate, etc,etc to make great UX. Even WPF has got a more closely matching control- ListView, which can be easily templated to give better UX than a traditional Datagrid like display. And I would say a readymade DataGrid control will kill or hide a lot of creativity and it surely will decrease the innovations in User Experience field. So what is your opinion about the need of DataGrid in WPF as a Framework component? If you feel it is necessary then is it just because the world is so used to the DatGrid way of data display for many years? Some other threads having the discussion about DatGrid are here and here Link to WPF ToolKit - Latest WPF DatGrid

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• [C++] Write connected components of a graph using Boost Graph

  - by conradlee

  I have an file that is a long list of weighted edges, in the following form node1_id node2_id weight node1_id node3_id weight and so on. So one weighted edge per line. I want to load this file into boost graph and find the connected components in the graph. Each of these connected components is a subgraph. For each of these component subgraphs, I want to write the edges in the above-described format. I want to do all this using boost graph. This problem is in principle simple, it's just I'm not sure how to implement it neatly because I don't know my way around Boost Graph. I have already spent some hours and have code that will find the connected components, but my version is surely much longer and more complicated that necessary---I'm hoping there's a boost-graph ninja out there that can show me the right, easy way.

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• ASP.NET MVC 2 RC2 Model Binding with NVARCHAR NOT NULL column

  - by Gary McGill

  I have a database column defined as NVARCHAR(1000) NOT NULL DEFAULT(N'') - in other words, a non-nullable text column with a default value of blank. I have a model class generated by the Linq-to-SQL Classes designer, which correctly identifies the property as not nullable. I have a TextAreaFor in my view for that property. I'm using UpdateModel in my controller to fetch the value from the form and populate the model object. If I view the web page and leave the text area blank, UpdateModel insists on setting the property to NULL instead of empty string. (Even if I set the value to blank in code prior to calling UpdateModel, it still overwrites that with NULL). Which, of course, causes the subsequent database update to fail. I could check all such properties for NULL after calling UpdateModel, but that seems ridiculous - surely there must be a better way? Please don't tell me I need a custom model binder for such a simple scenario...!

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• What's the convention for extending Linq with set based helper operations

  - by Luke Rohde

  Hi All I might be vaguing out here but I'm looking for a nice place to put set based helper operations in linq so I can do things like; db.Selections.ClearTemporary() which does something like db.DeleteAllOnSubmit(db.Selections.Where(s => s.Temporary)) Since I can figure out how to extend Table<Selection> the best I can do is create a static method in partial class of Selection (similar to Ruby) but I have to pass in the datacontext like; Selection.ClearTemporary(MyDataContext) This kind of sucks because I have two conventions for doing set based operations and I have to pass the data context to the static class. I've seen other people recommending piling helper methods into a partial of the datacontext like; myDataContext.ClearTemporarySelections(); But I feel this makes the dc a dumping ground for in-cohesive operations. Surely I'm missing something. I hope so. What's the convention? TIA

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• double.NaN Equality in MS Test

  - by RichK

  Why am I getting this result? [TestMethod] public void nan_test() { Assert.AreEqual(1, double.NaN, 1E-1); <-- Passes Assert.AreEqual(1, double.NaN); <-- Fails } What difference does the delta have in asserting NaN equals a number? Surely it should always return false. I am aware of IsNaN, but that's not useful here (see below). Background: I have a function returning NaN (erroneously) , it was meant to be a real number but the test still passed. I'm using the delta because it's double precision equality, the original test used 1E-9.

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• Explicit return from a Ruby method - implementation hiding, reuse and optimisations.

  - by Chris McCauley

  Hi, Rather than allowing a Ruby method to blindly return the last statement evaluated, is there any advantage to returning nil explicitly? In terms of implementation hiding and reuse, it seems dangerous to blindly allow the last expression evaluated to be returned - isn't there a danger that a user will rely on this only to get a nasty surprise when the implementation is modified? Surely returning nil would be better unless an explicit return value was given. Following on, is there an optimisation that Ruby can make when the return is a simple type rather than a reference to a more complex object? Chris

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• Why Do Browsers Leak Memory?

  - by Dane Balia

  A colleague and I were speaking about browsers (using browser control in a project), and it appears as plain as day that all browsers (Firefox, Chrome, IE, Opera) display the same characteristic or side-effect from their usage and that being 'Leaking Memory'. Can someone explain why that is the case? Surely as with any form of code, there should be proper garbage collection? PS. I've read about some defensive patterns on why this can happen from a developer's perspective. I am aware of an article Crockford wrote on IE; but why is the problem symptomatic of every browser? Thanks

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• Spring roo Vs (Wicket and Spring)

  - by Ketan Khairnar

  Spring roo is new framework and I found it very interesting. I have been working on web application for last 3-4 years and Always found JSPs are hard to maintain across teams if everyone is not disciplined enough about separation of markup and serverside logic. I have used JackBe/BackBase in last projects and I enjoyed xml templates working as views. This was much better than JSPs. But I couldnt automate webtests through selenium for backbase. I would be surely using Spring MVC (-view), Hibernate on the backend. I found Wicket as good alternative. Have you used wicket along with Spring and what was your experience?

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• What's the convention for extending Linq datacontext with set based helper operations specific to on

  - by Luke Rohde

  Hi All I might be vaguing out here but I'm looking for a nice place to put set based helper operations in linq so I can do things like; db.Selections.ClearTemporary() which does something like db.DeleteAllOnSubmit(db.Selections.Where(s => s.Temporary)) Since I can figure out how to extend Table<Selection> the best I can do is create a static method in partial class of Selection (similar to Ruby) but I have to pass in the datacontext like; Selection.ClearTemporary(MyDataContext) This kind of sucks because I have two conventions for doing set based operations and I have to pass the data context to the static class. I've seen other people recommending piling helper methods into a partial of the datacontext like; myDataContext.ClearTemporarySelections(); But I feel this makes the dc a dumping ground for in-cohesive operations. Surely I'm missing something. I hope so. What's the convention? TIA

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• best way to store 1:1 user relationships in relational database

  - by aharon

  What is the best way to store user relationships, e.g. friendships, that must be bidirectional (you're my friend, thus I'm your friend) in a rel. database, e.g. MYSql? I can think of two ways: Everytime a user friends another user, I'd add two rows to a database, row A consisting of the user id of the innitiating user followed by the UID of the accepting user in the next column. Row B would be the reverse. You'd only add one row, UID(initiating user) followed by UID(accepting user); and then just search through both columns when trying to figure out whether user 1 is a friend of user 2. Surely there is something better?

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• Rails: simple bundler question with ruby-openid

  - by Joern Akkermann

  Hi! I just installed the ruby-openid gem and then bundled it by entering gem 'ruby-openid', :require => 'openid' in the gemfile. Then I started bundle install and bundle lock. Everything worked fine so far. But how can I now access the classes of ruby-openid. OpenID::method won't work for me. It raises a not found error. What have I forgot or done wrong? I'm absolutely new to bundler and the internet full of solutions for various versions, but I need one solution that's surely working. I'm thankful for any help!

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• How do I draw a texture-mapped triangle in MATLAB?

  - by Petter

  I have a triangle in (u,v) coordinates in an image. I would like to draw this triangle at 3D coordinates (X,Y,Z) texture-mapped with the triangle in the image. Here, u,v,X,Y,Z are all vectors with three elements representing the three corners of the triangle. I have a very ugly, slow and unsatisfactory solution in which I (1) extract a rectangular part of the image, (2) transform it to 3D space with the transformation defined by the three points, (3) draw it with surface, and (4) finally masking out everything that is not part of the triangle with AlphaData. Surely there must be an easier way of doing this?

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• Explicit return form a Ruby method - implementation hiding, reuse and optimisations.

  - by Chris McCauley

  Hi, Rather than allowing a Ruby method to blindly return the last statement evaluated, is there any advantage to returning nil explicitly? In terms of implementation hiding and reuse, it seems dangerous to blindly allow the last expression evaluated to be returned - isn't there a danger that a user will rely on this only to get a nasty surprise when the implementation is modified? Surely returning nil would be better unless an explicit return value was given. Following on, is there an optimisation that Ruby can make when the return is a simple type rather than a reference to a more complex object? Chris

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• MVC: Model View Controller -- does the View call the Model?

  - by Gary Green

  I've been reading about MVC design for a while now and it seems officially the View calls objects and methods in the Model, builds and outputs a view. I think this is mainly wrong. The Controller should act and retrieve/update objects inside the Model, select an appropriate View and pass the information to it so it may display. Only crude and rudiementary PHP variables/simple if statements should appear inside the View. If the View gets the information it needs to display from the Model, surely there will be a lot of PHP inside the View -- completely violating the point of seperating presentation logic.

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• How to outperform this regex replacement?

  - by spender

  After considerable measurement, I have identified a hotspot in one of our windows services that I'd like to optimize. We are processing strings that may have multiple consecutive spaces in it, and we'd like to reduce to only single spaces. We use a static compiled regex for this task: private static readonly Regex regex_select_all_multiple_whitespace_chars = new Regex(@"\s+",RegexOptions.Compiled); and then use it as follows: var cleanString= regex_select_all_multiple_whitespace_chars.Replace(dirtyString.Trim(), " "); This line is being invoked several million times, and is proving to be fairly intensive. I've tried to write something better, but I'm stumped. Given the fairly modest processing requirements of the regex, surely there's something faster. Could unsafe processing with pointers speed things further?

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• Why a very good PHP framework - Qcodo (or Qcubed - its branch) - is so unpopular?

  - by Pawel

  I am wondering why this framework (QCodo) is almost forgotten and totally unpopular. I've started using it a few years ago and it is the only thing that keeps me with PHP. Yeah ... its development is stuck (that's why there is now more active branch Qcubed) but it is still very good piece of software. Its main advantages: Event driven (something like asp.net) no spaghetti code Powerful code generation good ORM follows DRY very simple AJAX support is fun to write Since then I wanted to be trendy and checked Django but I cannot write normal request-based web application (it just doesn't feel right). Don't believe? chess.com is written with it and surely there are plenty others. My 2 questions are: Have you heard of it (PHP people)? If you are using it what is your opinion about it (show us examples of your work) Thanks

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• What's going to replace HTML & CSS & JS?

  - by Nigel Thorne

  HTML and CSS are showing their age. SASS generates CSS (because CSS isn't clean enough). Graphic Designers don't work in HTML, they work in graphics tools then have to translate it to HTML/CSS. JavaScript has to have abstractions like jQuery, and CSS has a bunch of hacks to even start approaching consistent predictable user experience. It feels like people are doing some wonderful things despite the technologies, not because of them. Surely there is a better way?!? Something more closely aligned with the task at hand.. of providing a fluid intuitive (consistent) user experience to let users achieve their goals. Thoughts?

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• Admin user always prehend initial user

  - by StepH

  Using an InnoSetup script (that seems to work fine under XP/Vista), i've a strange behavior under Seven RC: here is the [Files] section: [Files] Source: *.ico; DestDir: {app}\bin; Flags: ignoreversion Source: dist\*.*; DestDir: {app}\bin; Flags: ignoreversion Source: catalog\*.*; DestDir: {userappdata}\JetWorksheet\catalog; Flags: recursesubdirs createallsubdirs onlyifdoesntexist uninsneveruninstall Source: wizards\*.*; DestDir: {userappdata}\JetWorksheet\wizards; Flags: recursesubdirs createallsubdirs onlyifdoesntexist uninsneveruninstall Source: images\*.*; DestDir: {userdocs}\JetWorksheet\images; Flags: recursesubdirs createallsubdirs Source: wordlists\*.*; DestDir: {userdocs}\JetWorksheet\wordlists; Flags: recursesubdirs createallsubdirs The problem is: In place of using the {userappdata} of the user that started the setup, all the data goes to the "Admin" directories... I'm surely missing somethings...

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• How to recover gracefully from a C# udp socket exception

  - by Gearoid Murphy

  Context: I'm porting a linux perl app to C#, the server listens on a udp port and maintains multiple concurrent dialogs with remote clients via a single udp socket. During testing, I send out high volumes of packets to the udp server, randomly restarting the clients to observe the server registering the new connections. The problem is this: when I kill a udp client, there may still be data on the server destined for that client. When the server tries to send this data, it gets an icmp "no service available" message back and consequently an exception occurs on the socket. I cannot reuse this socket, when I try to associate a C# async handler with the socket, it complains about the exception, so I have to close and reopen the udp socket on the server port. Is this the only way around this problem?, surely there's some way of "fixing" the udp socket, as technically, UDP sockets shouldn't be aware of the status of a remote socket? Any help or pointers would be much appreciated. Thanks.

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• Add Today's Date to SharePoint Master Page

  - by soniiic

  Surely there must be a simple way of putting a simple code block into a master page :( I've tried using the obvious <%= "Hello, World!" %> syntax but code blocks aren't allowed. Then tried a site column, but don't know how to use them. Then tried web zones but master pages can't use them. Tried putting a web part (which are super difficult to make and deploy btw) into the page layout, but it just doesn't render :/ All I want is something nice and simple at the top of my site which shows today's date and the format I want to use is DateTime.Today.ToString("ddd, d MMMM yyyy") (Otherwise I'm resorting to javascript document.write!) Thanks all,

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• Does python have one way of doing things?

  - by gath

  I have always seen in python articles/books that python is simple and it has only one way of doing things. I would like someone to explain to me this concept keeping in mind the example below, if i wanted to get the min and max values of sequence i would do the following; seq=[1,2,3,4,5,6] min(seq) #1 max(seq) #6 but i can also do this; seq[:1] #1 seq[-1] #6 surely this are two ways of doing one simple thing. This confuses me a bit. Gath

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