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• ASP.NET server data persistence

  - by Wayne Werner

  Hi, I'm not really sure exactly how the question should be phrased, so please be patient if I ask the wrong thing. I'm writing an ASP.NET application using VB as the code behind language. I have a data access class that connects to the DB to run the query (parameterized, of course), and another class to perform the validation tasks - I access this class from my aspx page. What I would like is to be able to store the data server side and wait for the user to choose from a few options based on the validity of the data. But unless my understanding is completely off, having persistent data objects on the server will give problems when multiple users connect? My ultimate goal is that once the data has been validated the end user can't modify it. Currently I'm validating the data, but I still have to retrieve it from the web form AFTER the user says OK, which obviously leaves open the possibility of injecting bad data either accidentally (unlikely) or on purpose (also unlikely for the use, but I'd prefer not to take the chance). So am I completely off in my understanding? If so, can someone point me to a resource that provides some instructions on keeping persistent data on the server, or provide instruction? Thanks!

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• MemoryFailPoint fires to early in WinXP 64

  - by msedi

  Hello, I have created a volume class (called VoxelVolume) with a self-organizing memory management, since the GC in C# didn't provide a good mechanism for managing contents of the volume for mapping, unmapping and remapping. Although I could have used the mechanisms of virtual memory, the problem is that the files are often too large to fit into the page file and I don't want to force the users to increase the pagefile size. Currently this system is working quite well and there is no problem in lacking resources and OutOfMemoryExceptions since the InsufficientMemoryException using the MemoryFailPoint works quite well. This was all testes on a 32bit WinXP system with 2GB of main memory. Running the same mechanism on 64bit system with 32GB of main memory also works well, but when the application runs the MemoryFailPoint suddenly throws an exception although 24GB of main memory are still free. Another point is when the MemoryFailPoint has fired once, it fires everytime and there is no chance to get rid of it. What I have read so far, that there is a small object and a large object heap (SOH and LOH). But only for the SOH the GC takes real care of and I can free the SOH from unused objects by applying GC.Collect() and GC.WaitForPendingFinalizers. The MemoryFailPoint is obviously the only way to get a little bit of control for the LOH, but since there is enough memory left on the system I see no reason why the MemoryFilePoint should fire. Is there any experience around here using the MemoryFailPoint? Thank you for your help Martin

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• How can i mock or test my deferred execution functionality?

  - by cottsak

  I have what could be seen as a bizarre hybrid of IQueryable<T> and IList<T> collections of domain objects passed up my application stack. I'm trying to maintain as much of the 'late querying' or 'lazy loading' as possible. I do this in two ways: By using a LinqToSql data layer and passing IQueryable<T>s through by repositories and to my app layer. Then after my app layer passing IList<T>s but where certain elements in the object/aggregate graph are 'chained' with delegates so as to defer their loading. Sometimes even the delegate contents rely on IQueryable<T> sources and the DataContext are injected. This works for me so far. What is blindingly difficult is proving that this design actually works. Ie. If i defeat the 'lazy' part somewhere and my execution happens early then the whole thing is a waste of time. I'd like to be able to TDD this somehow. I don't know a lot about delegates or thread safety as it applies to delegates acting on the same source. I'd like to be able to mock the DataContext and somehow trace both methods of deferring (IQueryable<T>'s SQL and the delegates) the loading so that i can have tests that prove that both functions are working at different levels/layers of the app/stack. As it's crucial that the deferring works for the design to be of any value, i'd like to see tests fail when i break the design at a given level (separate from the live implementation). Is this possible?

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• rails xml to active record object

  - by Brian D.

  I've been googling for a while to try and convert and incoming XML request into an active record object. I've tried using the ActiveRecordObject.new.from_xml method but it doesn't seem to handle relationships. For example, say I have the following xml: <blog> <title></title> <blog-pages> <blog-page> <page-number></page-number> <content></content> </blog-page> </blog-pages> </blog> And I have the following model objects: class Blog < ActiveRecord::Base has_many :blog_pages end class BlogPage < ActiveRecord::Base belongs_to :blog end Is there a way to convert the xml into a blog object WITH relationships? Or do I need to manually parse the XML? Thanks in advance.

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• OpenCV. cvFnName() works, but cv::FunName() doesn't work

  - by Innuendo

  I'm using OpenCV to write a plugin for a simulator. I've made an OpenCV project (single - not a plugin) and it works fine. When I added OpenCV libs to the plugin project, I added all libs required. Visual Studio 2010 doesn't highlight any code line with red. All looks fine and compiles fine. But in execution, the program halts with a Runtime Error on any cv::function. For example: cv::imread, or cv::imwrite. But if I replace them with cvLoadImage() and cvSaveImage(), it works fine. Why does this happen? I don't want to rewrite the whole script in old-api-style (cvFnName). It means I should change all Mat objects to IplImages, and so on. UPDATE: // preparing template ifstream ifile(tmplfilename); if ( !FILE_LOADED && ifile ) { // loading template file Mat tmpl = cv::imread(tmplfilename, 1); // << here occurs error FILE_LOADED = true; } Mat src; Bmp2Mat(hDC, hBitmap, src); TargetDetector detector(src, tmpl); detector.detectTarget(); If I change to: if ( !FILE_LOADED && ifile ) { IplImage* tmpl = 0; tmpl = cvLoadImage(tmplfilename, 1); // no error occurs } And then no error occurs. Early it displayed some Runtime Error. Now, I wanted to copy exact message and it just crashes the application (simulator, what I am pluginning). It displays window error - to kill process or no. (I can't show exact message, because I'm using russian windows now)

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• ios UITableView reloadData don't increase content height

  - by Zoltan Varadi

  I'm facing a strange error in my iOS app and haven't been able to figure out the reason why. In my UITableView i can add new cells, so i refresh the array that is the datasource and call reloadData. Everything works without error. The numberOfRowsInSection is called again, and it's value is one more than it's previous value was. The new cell even gets inserted at the bottom of the tableview, but i cant scroll down to it. I only know that it's there because the tableview bounces and i can see it. I'm guessing the tableview's content height is not getting increased for some reason, but i have no idea why. I'm using iOS 6 btw. Any help is very much appreciated! Thanks, Zoli EDIT, answers for Srikanth's questions: How is data getting added. There's an NSArray containing objects of a specific type. The array.count is the number of the number of cells. This NSArray gets its values from a database query. When you say, you are refreshing the array, what do you mean. By refreshing the array i mean i execute a new query in the database and put the results of this query into an NSArray. this will be the tableview's datasource array. Like this: dataSourceArray = [dbManager executeQuery]; [tableView reloadData]; Are you adding the data within the same view controller Yes. Can you show some code as to what you are doing See above. Is the table view at the root of the view controllers view or is it within another view The tableview is the main view's first child. Can you try adding data to the array at the beginning, so that you can view the cell being added at the top. I don't understand what you mean.

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• transfering a container of data to different classes

  - by user340699

  I am passing a vector of bids from Trader class to Simulator class.which class then passes it on to the auctioneer class.something seems messed up, can anyone spot it please. Below is part of the code: Error: 199 expected primary-expression before '&' token //Class of Origin of the vector. class Trader { private: int nextBidId; public: Trader(); ~Trader(){}; Bid getNextBid(); Bid getNextBid(int trdId, int qty, int price, char type); void loadRange( vector <Bid> & bids ) {} ; void loadRange(BidList &, int trdId, int qty, int price, char type, int size); }; //To be received by the Simulator class Simulator { vector <Bid> list; Trader trader; Auctioneer auctioneer; public: void run(); }; // Passing the vector into a function in simulator Simulator::accept_bids(bid_vector::const_iterator begin, bid_vector::const_iterator end){ vector<Bid>::iterator itr; } //Its journey should end with the Auctioneer. who displays the data class Auctioneer { public: vector <Bid>v2;// created a new vector to hold the objects void accept_bids(vector<Bid> & bids); void displayBids(){return bids} };

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• Fontforge finds no fonts

  - by user1858080

  I'm trying to make my c++ program detect installed fonts on my Win32 machine. I tried fontforge by taking the library from the GTK+ bundle. I use the following test code: #include<fontconfig.h> FcBool success = FcInit (); if ( !success ) { return false; } FcConfig *config = FcInitLoadConfigAndFonts (); if(!config) { return false; } FcChar8 *s, *file; FcPattern *p = FcPatternCreate(); FcObjectSet *os = FcObjectSetBuild (FC_FAMILY,NULL); FcFontSet *fs = FcFontList(config, p, os); LOG("Total fonts: %d\n", fs->nfont); for (int i=0; fs && i < fs->nfont; i++) { FcPattern *font = fs->fonts[i]; s = FcNameUnparse(font); LOG("Font: %s\n", s); free(s); if (FcPatternGetString(font, FC_FILE, 0, &file) == FcResultMatch) { LOG("Filename: %s\n", file); } } // destroy objects here ... Unfortunately this test application only prints: "Total fonts: 0" I know there are fonts installed on my machine and I know that Gimp2.0 detects them, so there must be somthing wrong with my test code. Does anyone have any idea? Besides linking the fontconfig-1.dll I did nothing special. I haven't created any config files or anything, because I couldn't read anywhere about having to do that. Please place any suggestions, thanks!

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• nhibernate mapping: delete collection, insert new collection with old IDs

  - by npeBeg

  my issue lokks similar to this one: (link) but i have one-to-many association: <set name="Fields" cascade="all-delete-orphan" lazy="false" inverse="true"> <key column="[TEMPLATE_ID]"></key> <one-to-many class="MyNamespace.Field, MyLibrary"/> </set> (i also tried to use ) this mapping is for Template object. this one and the Field object has their ID generators set to identity. so when i call session.Update for the Template object it works fine, well, almost: if the Field object has an Id number, UPDATE sql request is called, if the Id is 0, the INSERT is performed. But if i delete a Field object from the collection it has no effect for the Database. I found that if i also call session.Delete for this Field object, everything will be ok, but due to client-server architecture i don't know what to delete. so i decided to delete all the collection elements from the DB and call session.Update with a new collection. and i've got an issue: nhibernate performs the UPDATE operation for the Field objects that has non-zero Id, but they are removed from DB! maybe i should use some other Id generator or smth.. what is the best way to make nhibernate perform "delete all"/"insert all" routine for the collection?

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• Need an advice for unit testing using mock object

  - by Andree

  Hi there, I just recently read about "Mocking objects" for unit testing and currently I'm having a difficulties implementing this approach in my application. Please let me explain my problem. I have a User model class, which is dependent on 2 data sources (database and facebook web service). The controller class simply use this User model as an interface to access data and it doesn't care about where the data came from. Currently I never done any unit test to this User model because it is dependent on an external web service. But just a while ago, I read about object mocking and now I know that it is a common approach to unit test a class that depends on external resources (like in my case). Now I want to create a unit test for the User model, but then I encountered a design issue: In order for the User model to use a mocked Facebook SDK, I have to inject this mocked Facebook SDK to the User object (probably using a setter). Therefore I can't construct the Facebook SDK inside the User object. I have to construct it outside the User object, and inject the SDK into the User object. The real client of my User model is the application's controller. Therefore I have to construct the Facebook SDK inside the controller and inject it to the user object. Well, this is a problem because I want my controller to be as clean as possible. I want my controller to be ignorant about the application's data source. I'm not good at explaining something systematically, so you'll probably sleeping before reading this last paragraph. But anyway, I want to ask if anyone here ever encountered the same problem as mine? How do you solve this problem? Regards, Andree

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• WPF - Extend ListView with checkable AND selectable ListViewItems

  - by Marks

  Hi there. I already read many examples on extending ListViews with checkboxes bound with IsSelected. But I want something more. I want a seperation between the checked and selected state, so i get a ListBox that has a single selected item, but can have multiple checked items. Unfortunately ListViewItem does not have a property for checked and I dont see a possibility to get the ListView to work with a custom CheckableListViewItem. Of course i could use a List of objects with a checked property as ItemSource, but I dont think thats a good way to go. Checked or not is a matter of the list or item-container, not of the object listed in it. Beside that I dont want all my classes like user, role, group to have counterparts like checkableUser, checkableRole and checkableGroup. The behaviour i want can be easyly accomblished for the UI with a <DataTemplate x:Key="CheckBoxCell"> <StackPanel Orientation="Horizontal"> <CheckBox /> </StackPanel> </DataTemplate> and a <GridViewColumn CellTemplate="{StaticResource CheckBoxCell}" Width="30"/> But without a binding on the checkbox i cant check if it is checked or not. Is there any way to accomplish something like that? The perfect solution for me would be to have listView1.SelectedItem, listView1.CheckedItems and maybe a listView1.UncheckedItems and of course listView1.CheckItem and listView1.UncheckItem. Thanks for any help.

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• Does "delegate" mean a type or an object?

  - by Michal Czardybon

  Reading from MSDN: "A delegate is a type that references a method. Once a delegate is assigned a method, it behaves exactly like that method." Does then "delegate" mean a type or an object?! ...It cannot be both. It seems to me that the single word is used in two different meanings: a type containing a reference to a method of some specified signature, an object of that type, which can be actually called like a method. I would prefer a more precise vocabulary and use "delegate type" for the first case. I have been recently reading a lot about events and delegates and that ambiguity was making me confused many times. Some other uses of "delegate" word in MSDN in the first meaning: "Custom event delegates are needed only when an event generates event data" "A delegate declaration defines a class that is derived from the class System.Delegate" Some other uses of "delegate" word in MSDN in the second meaning: "specify a delegate that will be called upon the occurrence of some event" "Delegates are objects that refer to methods. They are sometimes described as type-safe function pointers" What do you think? Why did people from Microsoft introduced this ambiguity? Am I the only person to have conceptual problems with different notions being referenced with the same word.

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• How do I correct feature envy in this case?

  - by RMorrisey

  I have some code that looks like: class Parent { private Intermediate intermediateContainer; public Intermediate getIntermediate(); } class Intermediate { private Child child; public Child getChild() {...} public void intermediateOp(); } class Child { public void something(); public void somethingElse(); } class Client { private Parent parent; public void something() { parent.getIntermediate().getChild().something(); } public void somethingElse() { parent.getIntermediate().getChild().somethingElse(); } public void intermediate() { parent.getIntermediate().intermediateOp(); } } I understand that is an example of the "feature envy" code smell. The question is, what's the best way to fix it? My first instinct is to put the three methods on parent: parent.something(); parent.somethingElse(); parent.intermediateOp(); ...but I feel like this duplicates code, and clutters the API of the Parent class (which is already rather busy). Do I want to store the result of getIntermediate(), and/or getChild(), and keep my own references to these objects?

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• Object Design catalog and resources

  - by Tauren

  I'm looking for web sites, books, or other resources that provide a catalog of object designs used in common scenarios. I'm not looking for generic design patterns, but for samples of actual object designs that were used to solve real problems. For instance, I'm about to build an internal messaging system for a web application, similar to Facebook's messaging system. This system will allow administrators to send messages to all members, to selected groups of members, or to individuals. Members can send messages to other members or groups of members. Fairly common stuff and a feature that I'm sure thousands of web applications require. I know each situation is different and there are a million ways to design this solution. Although this scenario isn't really all that complex, I'm sure the basic design of the necessary objects and relationships for a system like this has already been done many times. It would be nice to review other similar designs before building my own. Is there a place where people can share their designs and others can browse/search through the catalog to review and provide feedback on them? StackOverflow could be used to a degree for this, but doesn't really provide a catalog of designs. Any other resources that would relate?

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• C++: Reference and Pointer question (example regarding OpenGL)

  - by Jay

  I would like to load textures, and then have them be used by multiple objects. Would this work? class Sprite { GLuint* mTextures; // do I need this to also be a reference? Sprite( GLuint* textures ) // do I need this to also be a reference? { mTextures = textures; } void Draw( textureNumber ) { glBindTexture( GL_TEXTURE_2D, mTextures[ textureNumber ] ); // drawing code } }; // normally these variables would be inputed, but I did this for simplicity. const int NUMBER_OF_TEXTURES = 40; const int WHICH_TEXTURE = 10; void main() { std::vector<GLuint> the_textures; the_textures.resize( NUMBER_OF_TEXTURES ); glGenTextures( NUMBER_OF_TEXTURES, &the_textures[0] ); // texture loading code Sprite the_sprite( &the_textures[0] ); the_sprite.Draw( WHICH_TEXTURE ); } And is there a different way I should do this, even if it would work? Thanks.

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• C++ design related question

  - by Kotti

  Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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• iPhone Development - calling external JSON API (will Apple reject?)

  - by RPM1984

  Ok guys, so im new to iPhone development, so apologies if this is a silly question, but before i actually create my app i want to know if this is possible, and if Apple will reject this. (Note this is all theoretical) So i'd have a API (.NET) that runs on a cloud server somewhere and can return HTML/JSON/XML. I'll have a website that can access this API and allow customers to do some stuff (but this is not important for this question). I would then like my iPhone app to make a call to this API which would return JSON data. So my iPhone app might make a call to http://myapp/Foos which would return a JSON string of Foo objects. The iPhone app would then parse this JSON and do some funky stuff with it. So, that's the background, now the questions: Is this possible? (that is, call an external cloud API over HTTP, parse JSON response?) What are the chances of Apple rejecting this application (because it would be calling a non-Apple API) Are there any limitations (security, libraries, etc) on the iPhone/Objective-C/Cocoa that might hinder this solution? On this website, they seem to be doing exactly what im asking. Thoughts, suggestions, links would be greatly appreciated...

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• How to print each object in a collection in a separate page in Silverlight

  - by Ash

  I would like to know if its possible to print each object in a collection in separate pages using Silverlight printing API. Suppose I have a class Label public class Label { public string Address { get; set; } public string Country { get; set; } public string Name { get; set; } public string Town { get; set; } } I can use print API and print like this. private PrintDocument pd; private void PrintButton_Click(object sender, RoutedEventArgs e) { pd.Print("Test Print"); } private void pd_PrintPage(object sender, PrintPageEventArgs e) { Label labelToPrint = new Label() { Name = "Fake Name", Address = "Fake Address", Country = "Fake Country", Town = "Town" }; var printpage = new LabelPrint(); printpage.DataContext = new LabelPrintViewModel(labelToPrint); e.PageVisual = printpage; } LabelPrint Xaml <StackPanel x:Name="LayoutRoot" VerticalAlignment="Center" HorizontalAlignment="Center"> <TextBlock Text="{Binding Name}" /> <TextBlock Text="{Binding Address}" /> <TextBlock Text="{Binding Town}" /> <TextBlock Text="{Binding Country}" /> </StackPanel> Now, say I've a collection of Label objects, List<Label> labels = new List<Label>() { labelToPrint, labelToPrint, labelToPrint, labelToPrint }; How can I print each object in the list in separate pages ? Thanks for any suggestions ..

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• Invoking a method overloaded where all arguments implement the same interface

  - by double07

  Hello, My starting point is the following: - I have a method, transform, which I overloaded to behave differently depending on the type of arguments that are passed in (see transform(A a1, A a2) and transform(A a1, B b) in my example below) - All these arguments implement the same interface, X I would like to apply that transform method on various objects all implementing the X interface. What I came up with was to implement transform(X x1, X x2), which checks for the instance of each object before applying the relevant variant of my transform. Though it works, the code seems ugly and I am also concerned of the performance overhead for evaluating these various instanceof and casting. Is that transform the best I can do in Java or is there a more elegant and/or efficient way of achieving the same behavior? Below is a trivial, working example printing out BA. I am looking for examples on how to improve that code. In my real code, I have naturally more implementations of 'transform' and none are trivial like below. public class A implements X { } public class B implements X { } interface X { } public A transform(A a1, A a2) { System.out.print("A"); return a2; } public A transform(A a1, B b) { System.out.print("B"); return a1; } // Isn't there something better than the code below??? public X transform(X x1, X x2) { if ((x1 instanceof A) && (x2 instanceof A)) { return transform((A) x1, (A) x2); } else if ((x1 instanceof A) && (x2 instanceof B)) { return transform((A) x1, (B) x2); } else { throw new RuntimeException("Transform not implemented for " + x1.getClass() + "," + x2.getClass()); } } @Test public void trivial() { X x1 = new A(); X x2 = new B(); X result = transform(x1, x2); transform(x1, result); }

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• Using Memcached in Python/Django - questions.

  - by Thomas

  I am starting use Memcached to make my website faster. For constant data in my database I use this: from django.core.cache import cache cache_key = 'regions' regions = cache.get(cache_key) if result is None: """Not Found in Cache""" regions = Regions.objects.all() cache.set(cache_key, regions, 2592000) #(2592000sekund = 30 dni) return regions For seldom changed data I use signals: from django.core.cache import cache from django.db.models import signals def nuke_social_network_cache(self, instance, **kwargs): cache_key = 'networks_for_%s' % (self.instance.user_id,) cache.delete(cache_key) signals.post_save.connect(nuke_social_network_cache, sender=SocialNetworkProfile) signals.post_delete.connect(nuke_social_network_cache, sender=SocialNetworkProfile) Is it correct way? I installed django-memcached-0.1.2, which show me: Memcached Server Stats Server Keys Hits Gets Hit_Rate Traffic_In Traffic_Out Usage Uptime 127.0.0.1 15 220 276 79% 83.1 KB 364.1 KB 18.4 KB 22:21:25 Can sombody explain what columns means? And last question. I have templates where I am getting much records from a few table (relationships). So in my view I get records from one table and in templates show it and related info from others. Generating page last a few seconds for very small table (<100records). Is it some easy way to cache queries from templates? Have I to do some big structure in my view (with all related tables), cache it and send to template?

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• Nhibernate + Gridview + TargetInvocationException

  - by Scott

  For our grid views, we're setting the data sources as a list of results from an Nhibernate query. We're using lazy loading, so the objects are actually proxied... most of the time. In some instances the list will consist of types of Student and Composition_Aop_Proxy_jklasjdkl31231, which implements the same members as the Student class. We've still got the session open, so the lazy loading would resolve fine, if GridView didn't throw an error about the different types in the gridview. Our current workaround is to clone the object, which results in fetching all of the data that can be lazily loaded, even though most of it won't be accessed.. ever. This, however, converts the proxy into an actual object and the grid view is happy. The performance implications kind of scare me as we're getting closer to rolling the code out as is. I've tried evicting the object after a save, which should ensure that everything is a proxy, but this doesn't seem like a good idea either. Does anyone have any suggestions/workarounds?

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• Dealing With Java Default Level Access Specifiers

  - by Tom Tresansky

  I've seen some code in a project recently where some fields in a couple classes have been using the default access modifier without good reason to. It almost looks like a case of "oops, forgot to make these private". Since the classes are used almost exclusively outside of the package they are defined in, the fields are not visible from the calling code, and are treated as private. So the mistake/oversight would not be very noticeable. However, encapsulation is broken. If I wanted to add a new class to the existing package, I could then mess with internal data in objects using fields with default access. So, my questions: Are there any best practices concerning default access specifiers that I should be aware of? Anything that would help prevent this type of accident from re-occurring? Are are any annotations which might say something to the effect of "I really meant for these to be default access"? Using CheckStyle, or any other Eclipse plugins, is there any way to flag instances of default fields, or disallow any not accompanied by, say, a "//default access" comment trailing them?

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• File.Replace throwing IOException

  - by WebDevHobo

  I have an app that can make modify images. In some cases, this makes the filesize smaller, in some cases bigger. The program doesn't have an option to "not replace the file if result has a bigger filesize". So I wrote a little C# app to try and solve this. Instead of overwriting the files, I make the app write the result to a folder under the current one and name that folder Test. The C# app I wrote compares grabs the contents of both folders and puts the full path to the file(s) in two List objects. I then compare and replace. The replacing isn't working however. I get the following IOException: Unable to remove the file to be replaced The location is on an external hard-drive, on which I have full rights. Now, I know I can just do File.Delete and File.Move in that order, but this exception has gotten me interested in why this particular setup wont work. Here's the source code: http://pastebin.com/4Vq82Umu And yes, the file specified as last argument of the Replace function does exist.

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• On the search for my next great .Net Read

  - by user127954

  Just got done with "The art of unit testing". It was a great read and i think everyone should go buy a copy. With that said i think the next book I'm like to read would be a architecture / Design type book that would focus heavily on building your objects / software in such a way that it would be: Low Coupling High Cohesion Easily Maintainable / Extended Easy to test Easy to Navigate / Debug The above characteristcs are the most important ones but also maybe it would also include (but not necessary) designing for: Performance - Don't want to design a system at at the end find out its dog slow :) Scalability - Again don't want to design something at the end find out it won't scale. I'd also prefer (but not necessary again): Something newer - Architectural principles seem to gradually evolve / improve over time and id like something with current thinking. .Net as illustrating language - like i said above its not mandatory but since its what i use every day id prefer it to be in .net. Doesn't really matter if its in vb.net or c# Some of the topics that would be talked about its how to minimize dependencies and using interfaces throughout your solution rather than concrete classes. Maybe it would constract /compare some of the newest design principles like DDD, Repository Pattern, Ect... I already have "Clean Code" (don't know if its this type of book or not) and "Working effectively with legacy code" on my radar but id like to read a book based upon the topic i talked about above first. Is there such a book?

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• GUID or int entity key with SQL Compact/EF4?

  - by David Veeneman

  This is a follow-up to an earlier question I posted on EF4 entity keys with SQL Compact. SQL Compact doesn't allow server-generated identity keys, so I am left with creating my own keys as objects are added to the ObjectContext. My first choice would be an integer key, and the previous answer linked to a blog post that shows an extension method that uses the Max operator with a selector expression to find the next available key: public static TResult NextId<TSource, TResult>(this ObjectSet<TSource> table, Expression<Func<TSource, TResult>> selector) where TSource : class { TResult lastId = table.Any() ? table.Max(selector) : default(TResult); if (lastId is int) { lastId = (TResult)(object)(((int)(object)lastId) + 1); } return lastId; } Here's my take on the extension method: It will work fine if the ObjectContext that I am working with has an unfiltered entity set. In that case, the ObjectContext will contain all rows from the data table, and I will get an accurate result. But if the entity set is the result of a query filter, the method will return the last entity key in the filtered entity set, which will not necessarily be the last key in the data table. So I think the extension method won't really work. At this point, the obvious solution seems to be to simply use a GUID as the entity key. That way, I only need to call Guid.NewGuid() method to set the ID property before I add a new entity to my ObjectContext. Here is my question: Is there a simple way of getting the last primary key in the data store from EF4 (without having to create a second ObjectContext for that purpose)? Any other reason not to take the easy way out and simply use a GUID? Thanks for your help.

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