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• Strange MSI error when setup.exe is run

  - by Martin Jackson

  We're using Visual Studio 2008's Setup Project to create an installer for our .NET 3.5 app. We host the .exe and .msi files on a website for our client to access, and produce new ones regularly to provide updates. This has all been fine until recently we've noticed some cases where installing via the .exe fails. The symptoms are: The .exe downloads fine, and runs fine. It appears to download the .msi successfully (the "downloading application files" step plods through happily), but then when it gets to the end of the "preparing to install" step, instead of launching the installer UI it pops up a message saying "This installation package could not be opened. Verify that the package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer package". You'd think that the .msi is just corrupt or something, but running it explicitly (even downloading it from the same location as the .exe to do so) works just fine. This problem is occurring on just some of our machines, which are running a mixture of XP and Windows7. The only pattern I can see in those machines that experience the problem is that they tend to have had the application installed on them longer (i.e. updating the app rather than installing for the first time). It seems to me that it might be something to do with how/where the .exe downloads the .msi to, and perhaps different versions are conflicting there? Has anyone experienced this before? Does anyone know where the installer .exe puts the .msi that it downloads?

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• Should DAL always return business objects in MVP

  - by Chathuranga

  In Model View Presenter (MVP) pattern, it is said that our DAL always should returns business models. But let's say if I want to get just a number from database like the last ClientID (the latest clients ID) which is a string, should my DAL method returns a ClientInfo object which has about 10 other fields as well like ClientName, Address etc.? If I want to get a list of business objects from my DAL, is it acceptable to do it as follows or better to get a DataTable from DAL and then in the applications BLL, converts it a List? public List<Employee> GetNewEmployees() { string selectStatement = "SELECT Employee.Emp_ID, Employee.Initials + ' ' + Employee.Surname AS Name,..."; using (SqlConnection sqlConnection = new SqlConnection(db.GetConnectionString)) { using (SqlCommand sqlCommand = new SqlCommand(selectStatement, sqlConnection)) { sqlConnection.Open(); using (SqlDataReader dataReader = sqlCommand.ExecuteReader()) { List<Employee> list = new List<Employee>(); while (dataReader.Read()) { list.Add ( new EpfEtfMaster { EmployeeID = (int) dataReader ["emp_id"], EmployeeName = (string) dataReader ["Name"], AppointmentDate = (DateTime) dataReader["appointment_date"], }); } return list; } } } }

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• How to avoid game rendering component circular references?

  - by CodexArcanum

  I'm working on a simple game design, and I wanted to break up my game objects into more reusable components. But I'm getting stuck on how exactly to implement the design I have in mind. Here's an example: I have a Logger object, whose job is simply to store a list of messages and render them to screen. You know, logging. Originally the Logger just held the list, and the game loop rendered it's contents. Then I moved the rendering logic into the Logger.Draw() method, and now I want to move it further into a LoggerRenderer object. In effect, I want to have the game loop call RenderAll, which will then call Logger.Render, which will in turn call the LoggerRenderer.Render and finally output the text. So the Logger needs to contain a Renderer object, but the Renderer needs access to the Logger's state (the message queue) in order to render. How do I resolve that? Should I be passing in the message queue and other state information explicitly to the Render method? Or should the game loop be calling the Renderer directly and it links back to the logger, but the RenderAll method never actually sees the logger object itself? This feels kind of like Command pattern, but I'm botching it up terribly.

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• problem generating pgp keys?

  - by pavankumar

  I'm using RSACryptoServiceProvider I've generated public key and private key. The keys generated by it are in the following format: Public key: <RSAKeyValue> <Modulus>m9bAoh2...eGNKYs=</Modulus> <Exponent>AQAB</Exponent> </RSAKeyValue> Private key: <RSAKeyValue> <Modulus>m9bAo...ZAIeGNKYs=</Modulus> <Exponent>AQAB</Exponent> <P>xGj/UcXs...R1lmeVQ==</P> <Q>yx6e18aP...GXzXIXw==</Q> <DP>NyxvnJ...1xAsEyQ==</DP> <DQ>La17Jycd...FhApEqwznQ==</DQ> <InverseQ>JrG7WCT...Hp3OWA==</InverseQ> <D>RdWsOFn....KL699Vh6HK0=</D> </RSAKeyValue> but using PGP Desktop i've generated keys like this - Public key: mQCNBEoOlp8BBACi/3EvBZ83ZduvG6YHu5F0P7Z3xOnpIsaPvTk0q+dnjwDUa5sU lEFbUZgDXSz7ZRhyiNqUOy+IG3ghPxpiKGBtldVpi33qaFCCEBiqsxRRpVCLgTUK HP2kH5ysrlFWkxTo =a4t9 Private key: lQHgBEoOlp8BBACi/3EvBZ83ZduvG6YHu5F0P7Z3xOnpIsaPvTk0q+dnjwDUa5sU lEFbUZgDXSz7ZRhyiNqUOy+IG3ghPxpiKGBtldVpi33qaFCCEBiqsxRRpVCLgTUK waBnEitQti3XgUUEZnz/rnXcQVM0QFBe6H5x8fMDUw== =CVPD So when I'm passing the keys generated by PGP Desktop it is able to do encryption and decryption perfectly but when im passing the keys generated by RSACryptoServiceProvider I'm not able to encrypt and decrypt? Can anyone please tell me how to generate keys in the pattern generated by PGP?

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• Good patterns for loose coupling in Java?

  - by Eye of Hell

  Hello. I'm new to java, and while reading documentation so far i can't find any good ways for programming with loose coupling between objects. For majority of languages i know (C++, C#, python, javascript) i can manage objects as having 'signals' (notification about something happens/something needed) and 'slots' (method that can be connected to signal and process notification/do some work). In all mentioned languages i can write something like this: Object1 = new Object1Class(); Object2 = new Object2Class(); Connect( Object1.ItemAdded, Object2.OnItemAdded ); Now if object1 calls/emits ItemAdded, the OnItemAdded method of Object2 will be called. Such loose coupling technique is often referred as 'delegates', 'signal-slot' or 'inversion of control'. Compared to interface pattern, technique mentioned don't need to group signals into some interfaces. Any object's methods can be connected to any delegate as long as signatures match ( C++Qt even extends this by allowing only partial signature match ). So i don't need to write additional interface code for each methods / groups of methods, provide default implementation for interface methods not used etc. And i can't see anything like this in Java :(. Maybe i'm looking a wrong way?

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• How to log correct context with Threadpool threads using log4net?

  - by myotherme

  I am trying to find a way to log useful context from a bunch of threads. The problem is that a lot of code is dealt with on Events that are arriving via threadpool threads (as far as I can tell) so their names are not in relation to any context. The problem can be demonstrated with the following code: class Program { private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType); static void Main(string[] args) { new Thread(TestThis).Start("ThreadA"); new Thread(TestThis).Start("ThreadB"); Console.ReadLine(); } private static void TestThis(object name) { var nameStr = (string)name; Thread.CurrentThread.Name = nameStr; log4net.ThreadContext.Properties["ThreadContext"] = nameStr; log4net.LogicalThreadContext.Properties["LogicalThreadContext"] = nameStr; log.Debug("From Thread itself"); ThreadPool.QueueUserWorkItem(x => log.Debug("From threadpool Thread: " + nameStr)); } } The Conversion pattern is: %date [%thread] %-5level %logger [%property] - %message%newline The output is like so: 2010-05-21 15:08:02,357 [ThreadA] DEBUG LogicalContextTest.Program [{LogicalThreadContext=ThreadA, log4net:HostName=xxx, ThreadContext=ThreadA}] - From Thread itself 2010-05-21 15:08:02,357 [ThreadB] DEBUG LogicalContextTest.Program [{LogicalThreadContext=ThreadB, log4net:HostName=xxx, ThreadContext=ThreadB}] - From Thread itself 2010-05-21 15:08:02,404 [7] DEBUG LogicalContextTest.Program [{log4net:HostName=xxx}] - From threadpool Thread: ThreadA 2010-05-21 15:08:02,420 [16] DEBUG LogicalContextTest.Program [{log4net:HostName=xxx}] - From threadpool Thread: ThreadB As you can see the last two rows have no Names of useful information to distinguish the 2 threads, other than manually adding the name to the message (which I want to avoid). How can I get the Name/Context into the log for the threadpool threads without adding it to the message at every call?

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• jQuery Tools alert works once (but only once)

  - by Jim Miller

  I'm trying to build a simple alert mechanism with jQuery Tools -- in response to a bit of Javascript code, pop up an overlay with a message and an OK button that, when clicked, makes the overlay go away. Trivial, or it should be. I've been slavishly following http://flowplayer.org/tools/demos/overlay/trigger.html, and have something that works fine the first time it's invoked, but only that time. If I repeat the JS action that should expose the overlay, it doesn't. My content/DIV: <div class='modal' id='the_alert'> <div id='modal_content' class='modal_content'> <h2>hi there</h2> this is the body <p> <button class='close'>OK</button> </p> </div> <div id='modal_background' class='modal_background'><img src='/images/overlay/f9f9f9-180.png' class='stretch' alt='' /></div> </div> and the Javascript: function showOverlayDialog() { $('#the_alert').overlay({ mask: {color: '#cccccc', loadSpeed: 200, opacity: 0.9}, closeOnClick: false, load: true }); } As I said: When showOverlayDialog() is invoked the first time, the overlay appears just like it should, and goes away when the "OK" button is clicked. But if I cause showOverlayDialog() to run again, without reloading the page, nothing happens. If I reload the page, then the pattern repeats -- the first invocation brings up the overlay, but the second one doesn't. I'm obviously missing something -- any advice out there? Thanks!

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• javascript regex: replace url text link with image,but not in html tags

  Hi this is my pice of code: <div style="overflow: hidden; width: 445px;">[IMG]http://i29.tinypic.com/mydog.png[/IMG] tak si to http://i29.tinypic.com/mycat.png Lorem ipsum loremai <img width="15" border="0" align="middle" src="images/smejo.gif" valign="middle"/> <img src=http://www.example.com/index.png alt> <img src="http://www.example.com/index.png" alt>     <a href="#reakcia" title="reagovat na temu"><span class="poradna-tl-reaguj"><reaction> </span></a></div> </td> </tr><img src=http://www.example.com/index.png alt><img src="http://www.example.com/index.png" alt> and i need regex pattern to replace ONLY text image links with image without touch of inner url tags. But i can't use "Lookbehind" or possessive quantifiers because JS don't support them=/ So i want to catch only "http://i29.tinypic.com/mydog.png" and "http://i29.tinypic.com/mycat.png". I using array method to replacing (will be greasemonkey script.) Many Thanks

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• Serializing MDI Winforms for persistency

  - by Serge

  Hello, basically my project is an MDI Winform application where a user can customize the interface by adding various controls and changing the layout. I would like to be able to save the state of the application for each user. I have done quite a bit of searching and found these: http://stackoverflow.com/questions/2076259/how-to-auto-save-and-auto-load-all-properties-in-winforms-c http://stackoverflow.com/questions/1669522/c-save-winform-or-controls-to-file Basically from what I understand, the best approach is to serialize the data to XML, however winform controls are not serializable, so I would have use surrogate classes: http://www.codeproject.com/KB/dotnet/Surrogate_Serialization.aspx Now, do I need to write a surrogate class for each of my controls? I would need to write some sort of a recursive algorithm to save all my controls, what is the best approach to do accomplish that? How would I then restore all the windows, should I use the memento design pattern for that? If I want to implement multiple users later, should I use Nhibernate to store all the object data in a database? I am still trying to wrap my head around the problem and if anyone has any experience or advice I would greatly appreciate it, thanks.

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• filterSecurityInterceptor and metadatasource implementation spring-security

  - by Mike

  Hi! I created a class that implements the FilterInvocationSecurityMetadataSource interface. I implemented it like this: public List<ConfigAttribute> getAttributes(Object object) { FilterInvocation fi = (FilterInvocation) object; Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal(); Long companyId = ((ExtenededUser) principal).getCompany().getId(); String url = fi.getRequestUrl(); // String httpMethod = fi.getRequest().getMethod(); List<ConfigAttribute> attributes = new ArrayList<ConfigAttribute>(); FilterSecurityService service = (FilterSecurityService) SpringBeanFinder.findBean("filterSecurityService"); Collection<Role> roles = service.getRoles(companyId); for (Role role : roles) { for (View view : role.getViews()) { if (view.getUrl().equalsIgnoreCase(url)) attributes.add(new SecurityConfig(role.getName() + "_" + role.getCompany().getName())); } } return attributes; } when I debug my application I see it reaches this class, it only reaches getAllConfigAttributes method, that is empty as I said, and return null. after that it prints this warning: Could not validate configuration attributes as the SecurityMetadataSource did not return any attributes from getAllConfigAttributes(). My aplicationContext- security is like this: <beans:bean id="filterChainProxy" class="org.springframework.security.web.FilterChainProxy"> <filter-chain-map path-type="ant"> <filter-chain filters="sif,filterSecurityInterceptor" pattern="/**" /> </filter-chain-map> </beans:bean> <beans:bean id="filterSecurityInterceptor" class="org.springframework.security.web.access.intercept.FilterSecurityInterceptor"> <beans:property name="authenticationManager" ref="authenticationManager" /> <beans:property name="accessDecisionManager" ref="accessDecisionManager" /> <beans:property name="securityMetadataSource" ref="filterSecurityMetadataSource" /> </beans:bean> <beans:bean id="filterSecurityMetadataSource" class="com.mycompany.filter.FilterSecurityMetadataSource"> </beans:bean> what could be the problem?

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• Troubleshooting ASP .NET Application on Shared Hosting

  - by James

  Hi, My company has a CRM site hosted externally on a shared server and recently it has been very problematic. Users are being logged out randomly, sometimes only seconds after logging in. We are also getting viewstate validation errors at times. Both problems seem to occur more often when there are two or more people logged in at the same time, but I can't really see any particular pattern. I am using log4net to track the application state and from what I can tell it seems that the application is frequently restarting, causing all sorts of issues. I can see log messages from the Application_Start event handler but there is not always a corresponding message from the Application_End event handler. There is also logging code in the Application_Error event handler but it is not catching anything at the time of the restart. These errors started to occur soon after we moved our site to this shared server, although I don't remember it being this bad at first. Any advice on how to track down these problems would be appreciated. The server is running Windows Server 2003 and IIS 6.0. Sadly I don't have access to the server other than through Parallels Plesk and it doesn't seem to have any useful diagnostic information.

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• Correct way to trigger object clone/memento when property changes

  - by Jay

  Hi, I have a big doubt about the correct way to save an object state (clone object), if necessary to rollback the changes, when a property has changed. I know that the IEditableObject interface exists for those cases but during some tests the BeginEdit would just fire like crazy (I have a DataGrid whose values can be edited but I won't need to keep the state of the object in these cases). I'm following the MVP design pattern in my project and the view's DataContext is a wrapper of my presenter.Let's say I have a CheckBox/TextBox in my UI and when that textbox's value changes, the property bound in the wrapper gets set.Currently, before setting the new value i'm raising an event to the presenter (something like PropertyChanging) that clones my wrapper. I'm doing this because I don't think that job should be done by the wrapper itself but by the presenter.Is this a correct approach? Raising the event is an acceptable solution? I thought of other possible ideas: Interface between presenter and wrapper; Use explicit binding and trigger the binding after saving object's state; What is your opinion about the best way to do this? Should I just keep IEditableObject, is this the best way? Best Regards

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• When virtual inheritance IS a good design?

  - by 7vies

  EDIT3: Please be sure to clearly understand what I am asking before answering (there are EDIT2 and lots of comments around). There are (or were) many answers which clearly show misunderstanding of the question (I know that's also my fault, sorry for that) Hi, I've looked over the questions on virtual inheritance (class B: public virtual A {...}) in C++, but did not find an answer to my question. I know that there are some issues with virtual inheritance, but what I'd like to know is in which cases virtual inheritance would be considered a good design. I saw people mentioning interfaces like IUnknown or ISerializable, and also that iostream design is based on virtual inheritance. Would those be good examples of a good use of virtual inheritance, is that just because there is no better alternative, or because virtual inheritance is the proper design in this case? Thanks. EDIT: To clarify, I'm asking about real-life examples, please don't give abstract ones. I know what virtual inheritance is and which inheritance pattern requires it, what I want to know is when it is the good way to do things and not just a consequence of complex inheritance. EDIT2: In other words, I want to know when the diamond hierarchy (which is the reason for virtual inheritance) is a good design

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• Resolving Circular References for Objects Implementing ISerializable

  - by Chris

  I'm writing my own IFormatter implementation and I cannot think of a way to resolve circular references between two types that both implement ISerializable. Here's the usual pattern: [Serializable] class Foo : ISerializable { private Bar m_bar; public Foo(Bar bar) { m_bar = bar; m_bar.Foo = this; } public Bar Bar { get { return m_bar; } } protected Foo(SerializationInfo info, StreamingContext context) { m_bar = (Bar)info.GetValue("1", typeof(Bar)); } public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("1", m_bar); } } [Serializable] class Bar : ISerializable { private Foo m_foo; public Foo Foo { get { return m_foo; } set { m_foo = value; } } public Bar() { } protected Bar(SerializationInfo info, StreamingContext context) { m_foo = (Foo)info.GetValue("1", typeof(Foo)); } public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("1", m_foo); } } I then do this: Bar b = new Bar(); Foo f = new Foo(b); bool equal = ReferenceEquals(b, b.Foo.Bar); // true // Serialise and deserialise b equal = ReferenceEquals(b, b.Foo.Bar); If I use an out-of-the-box BinaryFormatter to serialise and deserialise b, the above test for reference-equality returns true as one would expect. But I cannot conceive of a way to achieve this in my custom IFormatter. In a non-ISerializable situation I can simply revisit "pending" object fields using reflection once the target references have been resolved. But for objects implementing ISerializable it is not possible to inject new data using SerializationInfo. Can anyone point me in the right direction?

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• Data Access Layer, Best Practices

  - by labratmatt

  I'm looking for input on the best way to refactor the data access layer (DAL) in my PHP based web app. I follow an MVC pattern: PHP/HTML/CSS/etc. views on the front end, PHP controllers/services in the middle, and a PHP DAL sitting on top of a relational database in the model. Pretty standard stuff. Things are working fine, but my DAL is getting large (codesmell?) and becoming a bit unwieldy. My DAL contains almost all of the logic to interface with my database and is full of functions that look like this: function getUser($user_id) { $statement = "select id, name from users where user_id=:user_id"; PDO builds statement and fetchs results as an array return $array_of_results_generated_by_PDO_fetch_method; } Notes: The logic in my controller only interacts with the model using functions like the above in the DAL I am not using a framework (I'm of the opinion that PHP is a templating language and there's no need to inject complexity via a framework) I generally use PHP as a procedural language and tend to shy away from its OOP approach (I enjoy OOP development but prefer to keep that complexity out of PHP) What approaches have you taken when your DAL has reached this point? Do I have a fundamental design problem? Do I simply need to chop my DAL into a number of smaller files (logically divide it)? Thanks.

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• DDD: Persisting aggregates

  - by Mosh

  Hello, Let's consider the typical Order and OrderItem example. Assuming that OrderItem is part of the Order Aggregate, it an only be added via Order. So, to add a new OrderItem to an Order, we have to load the entire Aggregate via Repository, add a new item to the Order object and persist the entire Aggregate again. This seems to have a lot of overhead. What if our Order has 10 OrderItems? This way, just to add a new OrderItem, not only do we have to read 10 OrderItems, but we should also re-insert all these 10 OrderItems again. (This is the approach that Jimmy Nillson has taken in his DDD book. Everytime he wants to persists an Aggregate, he clears all the child objects, and then re-inserts them again. This can cause other issues as the ID of the children are changed everytime because of the IDENTITY column in database.) I know some people may suggest to apply Unit of Work pattern at the Aggregate Root so it keeps track of what has been changed and only commit those changes. But this violates Persistence Ignorance (PI) principle because persistence logic is leaking into the Domain Model. Has anyone thought about this before? Mosh

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• Is it valid to use unsafe struct * as an opaque type instead of IntPtr in .NET Platform Invoke?

  - by David Jeske

  .NET Platform Invoke advocates declaring pointer types as IntPtr. For example, the following [DllImport("user32.dll")] static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam); However, I find when interfacing with interesting native interfaces, that have many pointer types, flattening everything into IntPtr makes the code very hard to read and removes the typical typechecking that a compiler can do. I've been using a pattern where I declare an unsafe struct to be an opaque pointer type. I can store this pointer type in a managed object, and the compiler can typecheck it form me. For example: class Foo { unsafe struct FOO {}; // opaque type unsafe FOO *my_foo; class if { [DllImport("mydll")] extern static unsafe FOO* get_foo(); [DllImport("mydll")] extern static unsafe void do_something_foo(FOO *foo); } public unsafe Foo() { this.my_foo = if.get_foo(); } public unsafe do_something_foo() { if.do_something_foo(this.my_foo); } While this example may not seem different than using IntPtr, when there are several pointer types moving between managed and native code, using these opaque pointer types for typechecking is a godsend. I have not run into any trouble using this technique in practice. However, I also have not seen an examples of anyone using this technique, and I wonder why. Is there any reason that the above code is invalid in the eyes of the .NET runtime? My main question is about how the .NET GC system treats "unsafe FOO *my_foo". Is this pointer something the GC system is going to try to trace, or is it simply going to ignore it? My hope is that because the underlying type is a struct, and it's declared unsafe, that the GC would ignore it. However, I don't know for sure. Thoughts?

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• model view controller question

  - by songBong

  Hi, I've been working on my iphone game recently and came across a forked road when deciding the design of my various classes. So far I've adhered to the MVC pattern but the following situation had me confused: I have 4 buttons displayed visually. Each button though consists of a container UIView (which I've subclassed) and 2 UIButtons (also subclassed) as subviews. When you press a button, it does the flip effect plus other stuff. The user input is using target-action from my container UIView to my controller. This part is ok, the following part is the debatable part: So I've subclassed the container view as well as the UIButtons and I need to add more data/methods (somewhere) to do more things. Putting data that needs to be serialized and non-rendering related code in the view classes seems to break the MVC design but at the moment, it makes the most sense to me to put it there. It's almost like my subclassed views are their own little MVC's and it seems neat. Separating out the data/methods from the view to my main controller in this case seems unnecessary and a more work. How should I be doing it? Thanks heaps.

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• using indexer to retrieve Linq to SQL object from datastore

  - by fearofawhackplanet

  class UserDatastore : IUserDatastore { ... public IUser this[Guid userId] { get { User user = (from u in _dataContext.Users where u.Id == userId select u).FirstOrDefault(); return user; } } ... } One of the developers in our team is arguing that an indexer in the above situation is not appropriate and that a GetUser(Guid id) method should be prefered. The arguments being that: 1) We aren't indexing into an in-memory collection, the indexer is basically performing a hidden SQL query 2) Using a Guid in an indexer is bad (FxCop flagged this also) 3) Returning null from an indexer isn't normal behaviour 4) An API user generally wouldn't expect any of this behaviour I agree to an extent with (most of) these points. But I'm also inclined to argue that one of the characteristics of Linq is to abstract the database access to make it appear that you're simply working with a bunch of collections, even though the lazy evaluation paradigm means those collections aren't evaluated until you run a query over them. It doesn't seem inconsistent to me to access the datastore in the same manner as if it was a concrete in-memory collection here. Also bearing in mind this is an inherited codebase which uses this pattern extensively and consistently, is it worth the refactoring? I accept that it might have been better to use a Get method from the start, but I'm not yet convinced that it's completely incorrect to be using an indexer. I'd be interested to hear all opinions, thanks.

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• Linq to SQL generates StackOverflowException in tight Insert loop

  - by ChrisW

  I'm parsing an XML file and inserting the rows into a table (and related tables) using LinqToSQL. I parse the XML file using LinqToXml into IEnumerable. Then, I create a foreach loop, where I build my LinqToSQL objects and call InsertOnSubmit and SubmitChanges at the end of each loop. Nothing special here. Usually, I make it through around 4,100 records before receiving a StackOverflowException from LinqToSql, right as I call SubmitChanges. It's not always on 4,100... sometimes it's 4102, sometimes, less, etc. I've tried inserting the records that generate the failure individually, but putting them in their own Xml file, but that inserts fine... so it's not the data. I'm running the whole process from an MVC2 app that is uploading the Xml file to the server. I've adjusted my WebRequest timeouts to appropriate values, and again, I'm not getting timeout errors, just StackOverflowExceptions. So is there some pattern that I should follow for times when I have to do many insertions into the database? I never encounter this exception on smaller Xml files, just larger ones.

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• Most efficient way to check for DBNull and then assign to a variable?

  - by ilitirit

  This question comes up occasionally but I haven't seen a satisfactory answer. A typical pattern is (row is a DataRow): if (row["value"] != DBNull.Value) { someObject.Member = row["value"]; } My first question is which is more efficient (I've flipped the condition): row["value"] == DBNull.Value; // Or row["value"] is DBNull; // Or row["value"].GetType() == typeof(DBNull) // Or... any suggestions? This indicates that .GetType() should be faster, but maybe the compiler knows a few tricks I don't? Second question, is it worth caching the value of row["value"] or does the compiler optimize the indexer away anyway? eg. object valueHolder; if (DBNull.Value == (valueHolder = row["value"])) {} Disclaimers: row["value"] exists. I don't know the column index of the column (hence the column name lookup) I'm asking specifically about checking for DBNull and then assignment (not about premature optimization etc). Edit: I benchmarked a few scenarios (time in seconds, 10000000 trials): row["value"] == DBNull.Value: 00:00:01.5478995 row["value"] is DBNull: 00:00:01.6306578 row["value"].GetType() == typeof(DBNull): 00:00:02.0138757 Object.ReferenceEquals has the same performance as "==" The most interesting result? If you mismatch the name of the column by case (eg. "Value" instead of "value", it takes roughly ten times longer (for a string): row["Value"] == DBNull.Value: 00:00:12.2792374 The moral of the story seems to be that if you can't look up a column by it's index, then ensure that the column name you feed to the indexer matches the DataColumn's name exactly. Caching the value also appears to be nearly twice as fast: No Caching: 00:00:03.0996622 With Caching: 00:00:01.5659920 So the most efficient method seems to be: object temp; string variable; if (DBNull.Value != (temp = row["value"]) { variable = temp.ToString(); } This was a good learning experience.

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• Strange Ruby String Selection

  - by Daniel

  The string in question (read from a file): if (true) then { _this = createVehicle ["Land_hut10", [6226.8901, 986.091, 4.5776367e-005], [], 0, "CAN_COLLIDE"]; _vehicle_10 = _this; _this setDir -2.109278; }; Retrieved from a large list of similar (all same file) strings via the following: get_stringR(string,"if","};") And the function code: def get_stringR(a,b,c) b = a.index(b) b ||= 0 c = a.rindex(c) c ||= b r = a[b,c] return r end As so far, this works fine, but what I wanted to do is select the array after "createVehicle", the following (I thought) should work. newstring = get_string(myString,"\[","\];") Note get_string is the same as get_stringR, except it uses the first occurrence of the pattern both times, rather then the first and last occurrence. The output should have been: ["Land_hut10", [6226.8901, 986.091, 4.5776367e-005], [], 0, "CAN_COLLIDE"]; Instead it was the below, given via 'puts': ["Land_hut10", [6226.8901, 986.091, 4.5776367e-005], [], 0, "CAN_COLLIDE"]; _vehicle_10 = _this; _this setDir Some 40 characters past the point it should have retrieve, which was very strange... Second note, using both get_string and get_stringR produced the exact same result with the parameters given. I then decided to add the following to my get_string code: b = a.index(b) b ||= 0 c = a.index(c) c ||= b if c 40 then c -= 40 end r = a[b,c] return r And it works as expected (for every 'block' in the file, even though the strings after that array are not identical in any way), but something obviously isn't right :).

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• Word VBA - Find text between delimiters and convert to lower case

  - by jJack

  I would like to find text which is between the < and characters, and then turn any found text into "normal" case, where first letter of word is capitalized. Here is what I have thus far: Function findTextBetweenCarots() As String Dim strText As String With Selection .Find.Text = "<" ' what about <[^0-9]+> ? .Find.Forward = True .Find.Wrap = wdFindContinue End With Selection.Find.Execute ' Application.Selection. ' how do I get the text between the other ">"? findCarotSymb = Application.Selection.Text End Function Or, is there a better way of doing this? I also approached the problem using the VBScript Regex 5.5 library, which worked on simple documents, but not on certain documents with complex tables. For example, trying to just bold the text (for simplicity): Sub BoldUpperCaseWords() Dim regEx, Match, Matches Dim rngRange As Range Set regEx = New RegExp regEx.Pattern = "<[^0-9]+>" regEx.IgnoreCase = False regEx.Global = True Set Matches = regEx.Execute(ActiveDocument.Range.Text) For Each Match In Matches ActiveDocument.Range(Match.FirstIndex, Match.FirstIndex + Len(Match.Value)).Bold = True Next End Sub would not work in a document with tables. In fact, it would not even bold the correct text (the text between the <. This leads me to believe I have a broader issue here that I am missing. Here is what a sample doc looks like. Notice the wrong text is bold:

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• Is it immoral to write crappy code even if readability and correctness is not a requirement?

  - by mafutrct

  There are cases when crappy (i.e. unreadable and buggy) code is not much of a problem. For instance, imagine you need to generate a big text file that mostly follows a simple pattern with a few very complex exceptions. What do you do? You quickly write a simple algorithm and insert the exceptional bits in the output manually to save 4 hours. The code is unreadable, and the output is flawed, but it's still the correct way since it is way faster. But let's get this straight: I hate bad code. I've had to read and work with code that caused my stomach to hurt. I care a lot about good code. And actually, I caught myself thinking that it is immoral to write bad code even though the dirty approach is sometimes superior. I was surprised by myself and found my idea to be very irrational. Did you ever experience this? Should I just get rid of this stupid idea and use the most efficient approach to coding?

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• Elegant Algorithm for Parsing Data Stream Into Record

  - by Matt Long

  I am interfacing with a hardware device that streams data to my app over Wifi. The data is streaming in just fine. The data contains a character header (DATA:) that indicates a new record has begun. The issues is that the data I receive doesn't necessarily fall on the header boundary, so I have to capture the data until what I've captured contains the header. Then, everything that precedes the header goes into the previous record and everything that comes after it goes into a new record. I have this working, but wondered if anyone has done this before and has a good computer-sciencey way to solve the problem. Here's what I do: Convert the NSData of the current read to an NSString Append the NSString to a placeholder string Check placeholder string for the header (DATA:). If the header is not there, just wait for the next read. If the header exists, append whatever precedes it to a previous record placeholder and hand that placeholder off to an array as a complete record that I can further parse into fields. Take whatever shows up after the header and place it in the record placeholder so that it can be appended to in the next read. Repeat steps 3 - 5. Let me know if you see any flaws with this or have a suggestion for a better way. Seems there should be some design pattern for this, but I can't think of one. Thanks.

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