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  • Search in Projects API

    - by Geertjan
    Today I got some help from Jaroslav Havlin, the creator of the new "Search in Projects API". Below are the steps to create a search provider that finds recently modified files, via a new tab in the "Find in Projects" dialog: Here's how to get to the above result. Create a new NetBeans module project named "RecentlyModifiedFilesSearch". Then set dependencies on these libraries: Search in Projects API Lookup API Utilities API Dialogs API Datasystems API File System API Nodes API Create and register an implementation of "SearchProvider". This class tells the application the name of the provider and how it can be used. It should be registered via the @ServiceProvider annotation.Methods to implement: Method createPresenter creates a new object that is added to the "Find in Projects" dialog when it is opened. Method isReplaceSupported should return true if this provider support replacing, not only searching. If you want to disable the search provider (e.g., there aren't required external tools available in the OS), return false from isEnabled. Method getTitle returns a string that will be shown in the tab in the "Find in Projects" dialog. It can be localizable. Example file "org.netbeans.example.search.ExampleSearchProvider": package org.netbeans.example.search; import org.netbeans.spi.search.provider.SearchProvider; import org.netbeans.spi.search.provider.SearchProvider.Presenter; import org.openide.util.lookup.ServiceProvider; @ServiceProvider(service = SearchProvider.class) public class ExampleSearchProvider extends SearchProvider { @Override public Presenter createPresenter(boolean replaceMode) { return new ExampleSearchPresenter(this); } @Override public boolean isReplaceSupported() { return false; } @Override public boolean isEnabled() { return true; } @Override public String getTitle() { return "Recent Files Search"; } } Next, we need to create a SearchProvider.Presenter. This is an object that is passed to the "Find in Projects" dialog and contains a visual component to show in the dialog, together with some methods to interact with it.Methods to implement: Method getForm returns a JComponent that should contain controls for various search criteria. In the example below, we have controls for a file name pattern, search scope, and the age of files. Method isUsable is called by the dialog to check whether the Find button should be enabled or not. You can use NotificationLineSupport passed as its argument to set a display error, warning, or info message. Method composeSearch is used to apply the settings and prepare a search task. It returns a SearchComposition object, as shown below. Please note that the example uses ComponentUtils.adjustComboForFileName (and similar methods), that modifies a JComboBox component to act as a combo box for selection of file name pattern. These methods were designed to make working with components created in a GUI Builder comfortable. Remember to call fireChange whenever the value of any criteria changes. Example file "org.netbeans.example.search.ExampleSearchPresenter": package org.netbeans.example.search; import java.awt.FlowLayout; import javax.swing.BoxLayout; import javax.swing.JComboBox; import javax.swing.JComponent; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JSlider; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener; import org.netbeans.api.search.SearchScopeOptions; import org.netbeans.api.search.ui.ComponentUtils; import org.netbeans.api.search.ui.FileNameController; import org.netbeans.api.search.ui.ScopeController; import org.netbeans.api.search.ui.ScopeOptionsController; import org.netbeans.spi.search.provider.SearchComposition; import org.netbeans.spi.search.provider.SearchProvider; import org.openide.NotificationLineSupport; import org.openide.util.HelpCtx; public class ExampleSearchPresenter extends SearchProvider.Presenter { private JPanel panel = null; ScopeOptionsController scopeSettingsPanel; FileNameController fileNameComboBox; ScopeController scopeComboBox; ChangeListener changeListener; JSlider slider; public ExampleSearchPresenter(SearchProvider searchProvider) { super(searchProvider, false); } /** * Get UI component that can be added to the search dialog. */ @Override public synchronized JComponent getForm() { if (panel == null) { panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS)); JPanel row1 = new JPanel(new FlowLayout(FlowLayout.LEADING)); JPanel row2 = new JPanel(new FlowLayout(FlowLayout.LEADING)); JPanel row3 = new JPanel(new FlowLayout(FlowLayout.LEADING)); row1.add(new JLabel("Age in hours: ")); slider = new JSlider(1, 72); row1.add(slider); final JLabel hoursLabel = new JLabel(String.valueOf(slider.getValue())); row1.add(hoursLabel); row2.add(new JLabel("File name: ")); fileNameComboBox = ComponentUtils.adjustComboForFileName(new JComboBox()); row2.add(fileNameComboBox.getComponent()); scopeSettingsPanel = ComponentUtils.adjustPanelForOptions(new JPanel(), false, fileNameComboBox); row3.add(new JLabel("Scope: ")); scopeComboBox = ComponentUtils.adjustComboForScope(new JComboBox(), null); row3.add(scopeComboBox.getComponent()); panel.add(row1); panel.add(row3); panel.add(row2); panel.add(scopeSettingsPanel.getComponent()); initChangeListener(); slider.addChangeListener(new ChangeListener() { @Override public void stateChanged(ChangeEvent e) { hoursLabel.setText(String.valueOf(slider.getValue())); } }); } return panel; } private void initChangeListener() { this.changeListener = new ChangeListener() { @Override public void stateChanged(ChangeEvent e) { fireChange(); } }; fileNameComboBox.addChangeListener(changeListener); scopeSettingsPanel.addChangeListener(changeListener); slider.addChangeListener(changeListener); } @Override public HelpCtx getHelpCtx() { return null; // Some help should be provided, omitted for simplicity. } /** * Create search composition for criteria specified in the form. */ @Override public SearchComposition<?> composeSearch() { SearchScopeOptions sso = scopeSettingsPanel.getSearchScopeOptions(); return new ExampleSearchComposition(sso, scopeComboBox.getSearchInfo(), slider.getValue(), this); } /** * Here we return always true, but could return false e.g. if file name * pattern is empty. */ @Override public boolean isUsable(NotificationLineSupport notifySupport) { return true; } } The last part of our search provider is the implementation of SearchComposition. This is a composition of various search parameters, the actual search algorithm, and the displayer that presents the results.Methods to implement: The most important method here is start, which performs the actual search. In this case, SearchInfo and SearchScopeOptions objects are used for traversing. These objects were provided by controllers of GUI components (in the presenter). When something interesting is found, it should be displayed (with SearchResultsDisplayer.addMatchingObject). Method getSearchResultsDisplayer should return the displayer associated with this composition. The displayer can be created by subclassing SearchResultsDisplayer class or simply by using the SearchResultsDisplayer.createDefault. Then you only need a helper object that can create nodes for found objects. Example file "org.netbeans.example.search.ExampleSearchComposition": package org.netbeans.example.search; public class ExampleSearchComposition extends SearchComposition<DataObject> { SearchScopeOptions searchScopeOptions; SearchInfo searchInfo; int oldInHours; SearchResultsDisplayer<DataObject> resultsDisplayer; private final Presenter presenter; AtomicBoolean terminated = new AtomicBoolean(false); public ExampleSearchComposition(SearchScopeOptions searchScopeOptions, SearchInfo searchInfo, int oldInHours, Presenter presenter) { this.searchScopeOptions = searchScopeOptions; this.searchInfo = searchInfo; this.oldInHours = oldInHours; this.presenter = presenter; } @Override public void start(SearchListener listener) { for (FileObject fo : searchInfo.getFilesToSearch( searchScopeOptions, listener, terminated)) { if (ageInHours(fo) < oldInHours) { try { DataObject dob = DataObject.find(fo); getSearchResultsDisplayer().addMatchingObject(dob); } catch (DataObjectNotFoundException ex) { listener.fileContentMatchingError(fo.getPath(), ex); } } } } @Override public void terminate() { terminated.set(true); } @Override public boolean isTerminated() { return terminated.get(); } /** * Use default displayer to show search results. */ @Override public synchronized SearchResultsDisplayer<DataObject> getSearchResultsDisplayer() { if (resultsDisplayer == null) { resultsDisplayer = createResultsDisplayer(); } return resultsDisplayer; } private SearchResultsDisplayer<DataObject> createResultsDisplayer() { /** * Object to transform matching objects to nodes. */ SearchResultsDisplayer.NodeDisplayer<DataObject> nd = new SearchResultsDisplayer.NodeDisplayer<DataObject>() { @Override public org.openide.nodes.Node matchToNode( final DataObject match) { return new FilterNode(match.getNodeDelegate()) { @Override public String getDisplayName() { return super.getDisplayName() + " (" + ageInMinutes(match.getPrimaryFile()) + " minutes old)"; } }; } }; return SearchResultsDisplayer.createDefault(nd, this, presenter, "less than " + oldInHours + " hours old"); } private static long ageInMinutes(FileObject fo) { long fileDate = fo.lastModified().getTime(); long now = System.currentTimeMillis(); return (now - fileDate) / 60000; } private static long ageInHours(FileObject fo) { return ageInMinutes(fo) / 60; } } Run the module, select a node in the Projects window, press Ctrl-F, and you'll see the "Find in Projects" dialog has two tabs, the second is the one you provided above:

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  • Android Emulator - Ubuntu 12.04

    - by Aneesh karthik C
    When I type in the command @emulator Andreud where 'Andreud' is the name of the emulator I created. It gives the following errors and a blank screen in which I should get android home screen, icons, etc shows up. PVRDRIInitPVR2D: PVR2D device index (0)Failed to load libGL.so error libGL.so: cannot open shared object file: No such file or directory Failed to load libGL.so error libGL.so: cannot open shared object file: No such file or directory As per a comment I tried installing ia32-libs aneesh@nb14:~$ sudo apt-get install ia32-libs Reading package lists... Done Building dependency tree Reading state information... Done Package ia32-libs is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'ia32-libs' has no installation candidate I want the home screen to appear. Any help is greatly appreciated.

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  • Customizing / overriding ComboBox (2 replies)

    Hi, I would override a Windows.Forms.Combobox to have a MyObjectCollection instead of a ObjectCollection as Items property. I've try writing this code, but it seems that items are stored somewhere else (not in Items property). I can add items to collection but when I try to select an item from the combobox (at runtime) an exception tells me that there is no such element in Items (litterally it tel...

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  • IsNullOrEmpty generic method for Array to avoid Re-Sharper warning

    - by Michael Freidgeim
    I’ve used the following extension method in many places. public static bool IsNullOrEmpty(this Object[] myArr) { return (myArr == null || myArr.Length == 0); }Recently I’ve noticed that Resharper shows warning covariant array conversion to object[] may cause an exception for the following codeObjectsOfMyClass.IsNullOrEmpty()I’ve resolved the issue by creating generic extension method public static bool IsNullOrEmpty<T>(this T[] myArr) { return (myArr == null || myArr.Length == 0); }Related linkshttp://connect.microsoft.com/VisualStudio/feedback/details/94089/add-isnullorempty-to-array-class    public static bool IsNullOrEmpty(this System.Collections.IEnumerable source)        {            if (source == null)                return true;            else            {                return !source.GetEnumerator().MoveNext();            }        }http://stackoverflow.com/questions/8560106/isnullorempty-equivalent-for-array-c-sharp

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  • isometric background that covers the viewport [on hold]

    - by Richard
    The background image should cover the viewport. The technique I use now is a loop with an innerloop that draws diamond shaped images on a canvas element, but it looks like a rotated square. This is a nice example: ,that covers the whole viewport. I have heard something about clickthrough maps, but what more ways are there that are most efficient with mobile devices and javascript? Any advice in grid design out there?.

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  • Powershell – script all objects on all databases to files

    - by Nigel Rivett
    <# This simple PowerShell routine scripts out all the user-defined functions, stored procedures, tables and views in all the databases on the server that you specify, to the path that you specify. SMO must be installed on the machine (it happens if SSMS is installed) To run - set the servername and path Open a command window and run powershell Copy the below into the window and press enter - it should run It will create the subfolders for the databases and objects if necessary. #> $path = “C:\Test\Script\" $ServerName = "MyServerNameOrIpAddress" [System.Reflection.Assembly]::LoadWithPartialName('Microsoft.SqlServer.SMO') $serverInstance = New-Object ('Microsoft.SqlServer.Management.Smo.Server') $ServerName $IncludeTypes = @(“tables”,”StoredProcedures”,"Views","UserDefinedFunctions") $ExcludeSchemas = @(“sys”,”Information_Schema”) $so = new-object (‘Microsoft.SqlServer.Management.Smo.ScriptingOptions’) $so.IncludeIfNotExists = 0 $so.SchemaQualify = 1 $so.AllowSystemObjects = 0 $so.ScriptDrops = 0 #Script Drop Objects $dbs=$serverInstance.Databases foreach ($db in $dbs) { $dbname = "$db".replace("[","").replace("]","") $dbpath = "$path"+"$dbname" + "\" if ( !(Test-Path $dbpath)) {$null=new-item -type directory -name "$dbname"-path "$path"} foreach ($Type in $IncludeTypes) { $objpath = "$dbpath" + "$Type" + "\" if ( !(Test-Path $objpath)) {$null=new-item -type directory -name "$Type"-path "$dbpath"} foreach ($objs in $db.$Type) { If ($ExcludeSchemas -notcontains $objs.Schema ) { $ObjName = "$objs".replace("[","").replace("]","") $OutFile = "$objpath" + "$ObjName" + ".sql" $objs.Script($so)+"GO" | out-File $OutFile #-Append } } } }

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  • Motivation and use of move constructors in C++

    - by Giorgio
    I recently have been reading about move constructors in C++ (see e.g. here) and I am trying to understand how they work and when I should use them. As far as I understand, a move constructor is used to alleviate the performance problems caused by copying large objects. The wikipedia page says: "A chronic performance problem with C++03 is the costly and unnecessary deep copies that can happen implicitly when objects are passed by value." I normally address such situations by passing the objects by reference, or by using smart pointers (e.g. boost::shared_ptr) to pass around the object (the smart pointers get copied instead of the object). What are the situations in which the above two techniques are not sufficient and using a move constructor is more convenient?

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  • nVidia GeForce Go 7600? can it ever run unity?

    - by Khaled Musleh
    my laptop Toshiba Qosmio G30 has nVidia GeForce Go 7600 card and it suppose to support 3D . i run unity 2d now . I run 12.04 and the graphic driver is--VESA: G73 Board - toshg73m-- by UBUNTU. when i run /usr/lib/nux/unity_support_test -p then i get this list Not software rendered: no Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no the card is not blacklisted but a similar one with GT is! Do you think that there is a chance the laptop can run the unity 3d? and may be i could change the resolution of the screen to a higher one too! I tried all the nvidia drivers provided but none works (except 96 in ubuntu 12.04 ). i get a black screen or terminal screen. best wishes to all

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  • How to show other characters in online 2D rpg

    - by Loligans
    I have Player 1 and Player 2 I am using Json to send and retrieve player data between the client and the server, but when another player logs in, and is in the same map, how would I send that data to both players to update the graphics engine to show there are 2 Players on the map? About my game it is a 2D RPG tile based game it is 24x15 Tiles it is Real time Action it should interact anywhere between 10-150 ping players interact with each other when in the same map and can see each other moving around the game world is persistent, and is saved when the server shuts down Right now the server just sends the player Only their information which is inside a Json Object Here is an example of what I am talking about If you notice there are 2 separate characters in 2 separate clients, but they are running on the same server. I am trying to get them to show up on both clients, but I don't know how I should accomplish this. Should I send it as an added value in the Json object? Also what is the name of this process so I can look it up and find more info on it?

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  • The practical cost of swapping effects

    - by sebf
    Hello, I use XNA for my projects and on those forums I sometimes see references to the fact that swapping an effect for a mesh has a relatively high cost, which surprises me as I thought to swap an effect was simply a case of copying the replacement shader program to the GPU along with appropriate parameters. I wondered if someone could explain exactly what is costly about this process? And put, if possible, 'relatively' into context? For example say I wanted to use a short shader to help with picking, I would: Change the effect on every object, calculting a unique color to identify it and providing it to the shader. Draw all the objects to a render target in memory. Get the color from the target and use it to look up the selected object. What portion of the total time taken to complete that process would be spent swapping the shaders? My instincts would say that rendering the scene again, no matter how simple the shader, would be an order of magnitude slower than any other part of the process so why all the concern over effects?

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  • "Imprinting" as a language feature?

    - by MKO
    Idea I had this idea for a language feature that I think would be useful, does anyone know of a language that implements something like this? The idea is that besides inheritance a class can also use something called "imprinting" (for lack of better term). A class can imprint one or several (non-abstract) classes. When a class imprints another class it gets all it's properties and all it's methods. It's like the class storing an instance of the imprinted class and redirecting it's methods/properties to it. A class that imprints another class therefore by definition also implements all it's interfaces and it's abstract class. So what's the point? Well, inheritance and polymorphism is hard to get right. Often composition gives far more flexibility. Multiple inheritance offers a slew of different problems without much benefits (IMO). I often write adapter classes (in C#) by implementing some interface and passing along the actual methods/properties to an encapsulated object. The downside to that approach is that if the interface changes the class breaks. You also you have to put in a lot of code that does nothing but pass things along to the encapsulated object. A classic example is that you have some class that implements IEnumerable or IList and contains an internal class it uses. With this technique things would be much easier Example (c#) [imprint List<Person> as peopleList] public class People : PersonBase { public void SomeMethod() { DoSomething(this.Count); //Count is from List } } //Now People can be treated as an List<Person> People people = new People(); foreach(Person person in people) { ... } peopleList is an alias/variablename (of your choice)used internally to alias the instance but can be skipped if not needed. One thing that's useful is to override an imprinted method, that could be achieved with the ordinary override syntax public override void Add(Person person) { DoSomething(); personList.Add(person); } note that the above is functional equivalent (and could be rewritten by the compiler) to: public class People : PersonBase , IList<Person> { private List<Person> personList = new List<Person>(); public override void Add(object obj) { this.personList.Add(obj) } public override int IndexOf(object obj) { return personList.IndexOf(obj) } //etc etc for each signature in the interface } only if IList changes your class will break. IList won't change but an interface that you, someone in your team, or a thirdparty has designed might just change. Also this saves you writing a whole lot of code for some interfaces/abstract classes. Caveats There's a couple of gotchas. First we, syntax must be added to call the imprinted classes's constructors from the imprinting class constructor. Also, what happends if a class imprints two classes which have the same method? In that case the compiler would detect it and force the class to define an override of that method (where you could chose if you wanted to call either imprinted class or both) So what do you think, would it be useful, any caveats? It seems it would be pretty straightforward to implement something like that in the C# language but I might be missing something :) Sidenote - Why is this different from multiple inheritance Ok, so some people have asked about this. Why is this different from multiple inheritance and why not multiple inheritance. In C# methods are either virtual or not. Say that we have ClassB who inherits from ClassA. ClassA has the methods MethodA and MethodB. ClassB overrides MethodA but not MethodB. Now say that MethodB has a call to MethodA. if MethodA is virtual it will call the implementation that ClassB has, if not it will use the base class, ClassA's MethodA and you'll end up wondering why your class doesn't work as it should. By the terminology sofar you might already confused. So what happens if ClassB inherits both from ClassA and another ClassC. I bet both programmers and compilers will be scratching their heads. The benefit of this approach IMO is that the imprinting classes are totally encapsulated and need not be designed with multiple inheritance in mind. You can basically imprint anything.

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  • Stairway to XML: Level 5 - The XML exist() and nodes() Methods

    The XML exist() method is used, often in a WHERE clause, to check the existence of an element within an XML document or fragment. The nodes() method lets you shred an XML instance and return the information as relational data. 12 essential tools for database professionalsThe SQL Developer Bundle contains 12 tools designed with the SQL Server developer and DBA in mind. Try it now.

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  • Generically correcting data before save with Entity Framework

    - by koevoeter
    Been working with Entity Framework (.NET 4.0) for a week now for a data migration job and needed some code that generically corrects string values in the database. You probably also have seen things like empty strings instead of NULL or non-trimmed texts ("United States       ") in "old" databases, and you don't want to apply a correcting function on every column you migrate. Here's how I've done this (extending the partial class of my ObjectContext):public partial class MyDatacontext{    partial void OnContextCreated()    {        SavingChanges += OnSavingChanges;    }     private void OnSavingChanges(object sender, EventArgs e)    {        foreach (var entity in GetPersistingEntities(sender))        {            foreach (var propertyInfo in GetStringProperties(entity))            {                var value = (string)propertyInfo.GetValue(entity, null);                 if (value == null)                {                    continue;                }                 if (value.Trim().Length == 0 && IsNullable(propertyInfo))                {                    propertyInfo.SetValue(entity, null, null);                }                else if (value != value.Trim())                {                    propertyInfo.SetValue(entity, value.Trim(), null);                }            }        }    }     private IEnumerable<object> GetPersistingEntities(object sender)    {        return ((ObjectContext)sender).ObjectStateManager            .GetObjectStateEntries(EntityState.Added | EntityState.Modified)             .Select(e => e.Entity);    }    private IEnumerable<PropertyInfo> GetStringProperties(object entity)    {        return entity.GetType().GetProperties()            .Where(pi => pi.PropertyType == typeof(string));    }    private bool IsNullable(PropertyInfo propertyInfo)    {        return ((EdmScalarPropertyAttribute)propertyInfo             .GetCustomAttributes(typeof(EdmScalarPropertyAttribute), false)            .Single()).IsNullable;    }}   Obviously you can use similar code for other generic corrections.

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  • Having a generic data type for a database table column, is it "good" practice?

    - by Yanick Rochon
    I'm working on a PHP project where some object (class member) may contain different data type. For example : class Property { private $_id; // (PK) private $_ref_id; // the object reference id (FK) private $_name; // the name of the property private $_type; // 'string', 'int', 'float(n,m)', 'datetime', etc. private $_data; // ... // ..snip.. public getters/setters } Now, I need to perform some persistence on these objects. Some properties may be a text data type, but nothing bigger than what a varchar may hold. Also, later on, I need to be able to perform searches and sorting. Is it a good practice to use a single database table for this (ie. is there a non negligible performance impact)? If it's "acceptable", then what could be the data type for the data column?

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  • Updating a Progress Bar within the Status Bar [migrated]

    - by Muhnamana
    I'm trying to figure out how to incorporate a progress bar within the status bar to show how much processing is completed. Below is my example of updating the progress bar (not sure if this is the correct way or not) Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick ToolStripProgressBar1.Value = ToolStripProgressBar1.Value + 2 If ToolStripProgressBar1.Value = 100 Then ToolStripProgressBar1.Value = 0 ToolStripProgressBar1.Value = ToolStripProgressBar1.Value + 2 Timer1.Enabled = True End If End Sub Here is the code within the button. Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1Run.Click ToolStripStatusLabel1.Text = "Processing..." Timer1.Enabled = True 'more code to be inserted here End Sub What I'm not sure is how to update the progress bar based on the amount of code you have and once the processing is complete, update the ToolStripStatusLabel1 to show "Processing...Complete!".

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  • Why Keyword Research Should Come First

    Every online business should begin with keywords research and analysis. Unfortunately, there are a great number of online entrepreneurs that focus on site construction first before they think of this fundamental element. Not tackling keyword units first can lead to certain difficulties.

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  • NHibernate Tutorial #5 - Working with Many to Many relationships

    - by BobPalmer
    After a short break last week, I wanted to make sure I made time to publish the next in my series of tutorials on NHibernate. This week I'll be covering Many to Many relationships, the hilo algorithm, IdBag element, and touch on Lazy Loading. You can view the entire article at this link: http://docs.google.com/Doc?docid=0AUP-rKyyUMKhZGczejdxeHZfMjZkdjd3cjJnMg&hl=en As always, feedback and any technical bits I may have missed are always appreciated! -Bob Palmer

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  • The Human Significance of Article Writing in Link Building

    Internet marketing is highly dependent on good content. It goes without saying that for any website the content that is presented on it is just as important as anything other element of link building. Not only does good content help establish credibility but also carries many responsibilities also.

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  • Developing Schema Compare for Oracle (Part 5): Query Snapshots

    - by Simon Cooper
    If you've emailed us about a bug you've encountered with the EAP or beta versions of Schema Compare for Oracle, we probably asked you to send us a query snapshot of your databases. Here, I explain what a query snapshot is, and how it helps us fix your bug. Problem 1: Debugging users' bug reports When we started the Schema Compare project, we knew we were going to get problems with users' databases - configurations we hadn't considered, features that weren't installed, unicode issues, wierd dependencies... With SQL Compare, users are generally happy to send us a database backup that we can restore using a single RESTORE DATABASE command on our test servers and immediately reproduce the problem. Oracle, on the other hand, would be a lot more tricky. As Oracle generally has a 1-to-1 mapping between instances and databases, any databases users sent would have to be restored to their own instance. Furthermore, the number of steps required to get a properly working database, and the size of most oracle databases, made it infeasible to ask every customer who came across a bug during our beta program to send us their databases. We also knew that there would be lots of issues with data security that would make it hard to get backups. So we needed an easier way to be able to debug customers issues and sort out what strange schema data Oracle was returning. Problem 2: Test execution time Another issue we knew we would have to solve was the execution time of the tests we would produce for the Schema Compare engine. Our initial prototype showed that querying the data dictionary for schema information was going to be slow (at least 15 seconds per database), and this is generally proportional to the size of the database. If you're running thousands of tests on the same databases, each one registering separate schemas, not only would the tests would take hours and hours to run, but the test servers would be hammered senseless. The solution To solve these, we needed to be able to populate the schema of a database without actually connecting to it. Well, the IDataReader interface is the primary way we read data from an Oracle server. The data dictionary queries we use return their data in terms of simple strings and numbers, which we then process and reconstruct into an object model, and the results of these queries are identical for identical schemas. So, we can record the raw results of the queries once, and then replay these results to construct the same object model as many times as required without needing to actually connect to the original database. This is what query snapshots do. They are binary files containing the raw unprocessed data we get back from the oracle server for all the queries we run on the data dictionary to get schema information. The core of the query snapshot generation takes the results of the IDataReader we get from running queries on Oracle, and passes the row data to a BinaryWriter that writes it straight to a file. The query snapshot can then be replayed to create the same object model; when the results of a specific query is needed by the population code, we can simply read the binary data stored in the file on disk and present it through an IDataReader wrapper. This is far faster than querying the server over the network, and allows us to run tests in a reasonable time. They also allow us to easily debug a customers problem; using a simple snapshot generation program, users can generate a query snapshot that could be sent along with a bug report that we can immediately replay on our machines to let us debug the issue, rather than having to obtain database backups and restore databases to test systems. There are also far fewer problems with data security; query snapshots only contain schema information, which is generally less sensitive than table data. Query snapshots implementation However, actually implementing such a feature did have a couple of 'gotchas' to it. My second blog post detailed the development of the dependencies algorithm we use to ensure we get all the dependencies in the database, and that algorithm uses data from both databases to find all the needed objects - what database you're comparing to affects what objects get populated from both databases. We get information on these additional objects using an appropriate WHERE clause on all the population queries. So, in order to accurately replay the results of querying the live database, the query snapshot needs to be a snapshot of a comparison of two databases, not just populating a single database. Furthermore, although the code population queries (eg querying all_tab_cols to get column information) can simply be passed straight from the IDataReader to the BinaryWriter, we need to hook into and run the live dependencies algorithm while we're creating the snapshot to ensure we get the same WHERE clauses, and the same query results, as if we were populating straight from a live system. We also need to store the results of the dependencies queries themselves, as the resulting dependency graph is stored within the OracleDatabase object that is produced, and is later used to help order actions in synchronization scripts. This is significantly helped by the dependencies algorithm being a deterministic algorithm - given the same input, it will always return the same output. Therefore, when we're replaying a query snapshot, and processing dependency information, we simply have to return the results of the queries in the order we got them from the live database, rather than trying to calculate the contents of all_dependencies on the fly. Query snapshots are a significant feature in Schema Compare that really helps us to debug problems with the tool, as well as making our testers happier. Although not really user-visible, they are very useful to the development team to help us fix bugs in the product much faster than we otherwise would be able to.

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  • Enum types, FlagAttribute & Zero value

    - by nmgomes
    We all know about Enums types and use them every single day. What is not that often used is to decorate the Enum type with the FlagsAttribute. When an Enum type has the FlagsAttribute we can assign multiple values to it and thus combine multiple information into a single enum. The enum values should be a power of two so that a bit set is achieved. Here is a typical Enum type: public enum OperationMode { /// <summary> /// No operation mode /// </summary> None = 0, /// <summary> /// Standard operation mode /// </summary> Standard = 1, /// <summary> /// Accept bubble requests mode /// </summary> Parent = 2 } In such scenario no values combination are possible. In the following scenario a default operation mode exists and combination is used: [Flags] public enum OperationMode { /// <summary> /// Asynchronous operation mode /// </summary> Async = 0, /// <summary> /// Synchronous operation mode /// </summary> Sync = 1, /// <summary> /// Accept bubble requests mode /// </summary> Parent = 2 } Now, it’s possible to do statements like: [DefaultValue(OperationMode.Async)] [TypeConverter(typeof(EnumConverter))] public OperationMode Mode { get; set; } /// <summary> /// Gets a value indicating whether this instance supports request from childrens. /// </summary> public bool IsParent { get { return (this.Mode & OperationMode.Parent) == OperationMode.Parent; } } or switch (this.Mode) { case OperationMode.Sync | OperationMode.Parent: Console.WriteLine("Sync,Parent"); break;[…]  But there is something that you should never forget: Zero is the absorber element for the bitwise AND operation. So, checking for OperationMode.Async (the Zero value) mode just like the OperationMode.Parent mode makes no sense since it will always be true: (this.Mode & 0x0) == 0x0 Instead, inverse logic should be used: OperationMode.Async = !OperationMode.Sync public bool IsAsync { get { return (this.Mode & ContentManagerOperationMode.Sync) != ContentManagerOperationMode.Sync; } } or public bool IsAsync { get { return (int)this.Mode == 0; } } Final Note: Benefits Allow multiple values combination The above samples snippets were taken from an ASP.NET control and enabled the following markup usage: <my:Control runat="server" Mode="Sync,Parent"> Drawback Zero value is the absorber element for the bitwise AND operation Be very carefully when evaluating the Zero value, either evaluate the enum value as an integer or use inverse logic.

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  • Passing a parameter so that it cannot be changed – C#

    - by nmarun
    I read this requirement of not allowing a user to change the value of a property passed as a parameter to a method. In C++, as far as I could recall (it’s been over 10 yrs, so I had to refresh memory), you can pass ‘const’ to a function parameter and this ensures that the parameter cannot be changed inside the scope of the function. There’s no such direct way of doing this in C#, but that does not mean it cannot be done!! Ok, so this ‘not-so-direct’ technique depends on the type of the parameter – a simple property or a collection. Parameter as a simple property: This is quite easy (and you might have guessed it already). Bulent Ozkir clearly explains how this can be done here. Parameter as a collection property: Obviously the above does not work if the parameter is a collection of some type. Let’s dig-in. Suppose I need to create a collection of type KeyTitle as defined below. 1: public class KeyTitle 2: { 3: public int Key { get; set; } 4: public string Title { get; set; } 5: } My class is declared as below: 1: public class Class1 2: { 3: public Class1() 4: { 5: MyKeyTitleList = new List<KeyTitle>(); 6: } 7: 8: public List<KeyTitle> MyKeyTitleList { get; set; } 9: public ReadOnlyCollection<KeyTitle> ReadonlyKeyTitleCollection 10: { 11: // .AsReadOnly creates a ReadOnlyCollection<> type 12: get { return MyKeyTitleList.AsReadOnly(); } 13: } 14: } See the .AsReadOnly() method used in the second property? As MSDN says it: “Returns a read-only IList<T> wrapper for the current collection.” Knowing this, I can implement my code as: 1: public static void Main() 2: { 3: Class1 class1 = new Class1(); 4: class1.MyKeyTitleList.Add(new KeyTitle { Key = 1, Title = "abc" }); 5: class1.MyKeyTitleList.Add(new KeyTitle { Key = 2, Title = "def" }); 6: class1.MyKeyTitleList.Add(new KeyTitle { Key = 3, Title = "ghi" }); 7: class1.MyKeyTitleList.Add(new KeyTitle { Key = 4, Title = "jkl" }); 8:  9: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 10:  11: Console.ReadLine(); 12: } 13:  14: private static void TryToModifyCollection(ReadOnlyCollection<KeyTitle> readOnlyCollection) 15: { 16: // can only read 17: for (int i = 0; i < readOnlyCollection.Count; i++) 18: { 19: Console.WriteLine("{0} - {1}", readOnlyCollection[i].Key, readOnlyCollection[i].Title); 20: } 21: // Add() - not allowed 22: // even the indexer does not have a setter 23: } The output is as expected: The below image shows two things. In the first line, I’ve tried to access an element in my read-only collection through an indexer. It shows that the ReadOnlyCollection<> does not have a setter on the indexer. The second line tells that there’s no ‘Add()’ method for this type of collection. The capture below shows there’s no ‘Remove()’ method either, there-by eliminating all ways of modifying a collection. Mission accomplished… right? Now, even if you have a collection of different type, all you need to do is to somehow cast (used loosely) it to a List<> and then do a .AsReadOnly() to get a ReadOnlyCollection of your custom collection type. As an example, if you have an IDictionary<int, string>, you can create a List<T> of this type with a wrapper class (KeyTitle in our case). 1: public IDictionary<int, string> MyDictionary { get; set; } 2:  3: public ReadOnlyCollection<KeyTitle> ReadonlyDictionary 4: { 5: get 6: { 7: return (from item in MyDictionary 8: select new KeyTitle 9: { 10: Key = item.Key, 11: Title = item.Value, 12: }).ToList().AsReadOnly(); 13: } 14: } Cool huh? Just one thing you need to know about the .AsReadOnly() method is that the only way to modify your ReadOnlyCollection<> is to modify the original collection. So doing: 1: public static void Main() 2: { 3: Class1 class1 = new Class1(); 4: class1.MyKeyTitleList.Add(new KeyTitle { Key = 1, Title = "abc" }); 5: class1.MyKeyTitleList.Add(new KeyTitle { Key = 2, Title = "def" }); 6: class1.MyKeyTitleList.Add(new KeyTitle { Key = 3, Title = "ghi" }); 7: class1.MyKeyTitleList.Add(new KeyTitle { Key = 4, Title = "jkl" }); 8: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 9:  10: Console.WriteLine(); 11:  12: class1.MyKeyTitleList.Add(new KeyTitle { Key = 5, Title = "mno" }); 13: class1.MyKeyTitleList[2] = new KeyTitle{Key = 3, Title = "GHI"}; 14: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 15:  16: Console.ReadLine(); 17: } Gives me the output of: See that the second element’s Title is changed to upper-case and the fifth element also gets displayed even though we’re still looping through the same ReadOnlyCollection<KeyTitle>. Verdict: Now you know of a way to implement ‘Method(const param1)’ in your code!

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  • Why does creating dynamic bodies in JBox2D freeze my app?

    - by Amplify91
    My game hangs/freezes when I create dynamic bullet objects with Box2D and I don't know why. I am making a game where the main character can shoot bullets by the user tapping on the screen. Each touch event spawns a new FireProjectileEvent that is handled properly by an event queue. So I know my problem is not trying to create a new body while the box2d world is locked. My bullets are then created and managed by an object pool class like this: public Projectile getProjectile(){ for(int i=0;i<mProjectiles.size();i++){ if(!mProjectiles.get(i).isActive){ return mProjectiles.get(i); } } return mSpriteFactory.createProjectile(); } mSpriteFactory.createProjectile() leads to the physics component of the Projectile class creating its box2d body. I have narrowed the issue down to this method and it looks like this: public void create(World world, float x, float y, Vec2 vertices[], boolean dynamic){ BodyDef bodyDef = new BodyDef(); if(dynamic){ bodyDef.type = BodyType.DYNAMIC; }else{ bodyDef.type = BodyType.STATIC; } bodyDef.position.set(x, y); mBody = world.createBody(bodyDef); PolygonShape dynamicBox = new PolygonShape(); dynamicBox.set(vertices, vertices.length); FixtureDef fixtureDef = new FixtureDef(); fixtureDef.shape = dynamicBox; fixtureDef.density = 1.0f; fixtureDef.friction = 0.0f; mBody.createFixture(fixtureDef); mBody.setFixedRotation(true); } If the dynamic parameter is set to true my game freezes before crashing, but if it is false, it will create a projectile exactly how I want it just doesn't function properly (because a projectile is not a static object). Why does my program fail when I try to create a dynamic object at runtime but not when I create a static one? I have other dynamic objects (like my main character) that work fine. Any help would be greatly appreciated. This is a screenshot of a method profile I did: Especially notable is number 8. I'm just still unsure what I'm doing wrong. Other notes: I am using JBox2D 2.1.2.2. (Upgraded from 2.1.2.1 to try to fix this problem) When the application freezes, if I hit the back button, it appears to move my game backwards by one update tick. Very strange.

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  • Requriing static class setter to be called before Constructor, bad design?

    - by roverred
    I have a class, say Foo, and every instance of Foo will need and contain the same List object, myList. Since every class instance will share the same List Object, I thought it would be good to make myList static and use a static function to set myList before the constructor is called. I was wondering if this was bad, because this requires the setter to be called before the constructor. If the person doesn't, the program will crash. Alternative way would be passing myList every time. Thanks.

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  • WCF web service with Neural Network

    - by Gary Frank
    I am developing a web service that performs object recognition. It will be available for testing as soon as enough code has been developed, and then officially when it is finished. It is based on a radically new type of artificial neural network that I designed. Its goal is to recognize any type of object within an image. Besides the WCF web service, the project will also create a website to test and demonstrate the web service. Here is a link with more information. http://www.indiegogo.com/VOR

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  • Would like some help in understanding rendering geometry vs textures

    - by Anon
    So I was just pondering whether it is more taxing on the GPU to render geometry or a texture. What I'm trying to see is whether there is a huge difference in rendering two scenes with the same setup: Scene 1: Example Object: A dirt road (nothing else) Geometry: Detailed road, with all the bumps, cracks and so forth done in the mesh Scene 2: Example Object: A dirt road (nothing else) Geometry: A simple mesh, in a form of a road, but in this case maps and textures are simulating cracks, bumps, etc... So of these two, which one is likely to tax the hardware more? Or is it not a like for like comparison? What would be the best way of doing something like this? Go heavy on the textures? Or have a blend of both?

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