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Powershell - Using variables in -Include filter

- by TheD

(again!) My final question for the night. I have a function which uses the Get-ChildItem to work out the newest file within a folder. The reason being I need to find the latest incremental backup in a folder and script an EXE to mount it. However, within this same folder there are multiple backup chains for all different servers: i.e. SERVER1_C_VOL_b001_i015.spi SERVER2_D_VOL_b001_i189.spi SERVER1_C_VOL_b002_i091.spi SERVER1_E_VOL_b002_i891.spi (this is the newest file created) I want only to look at SERVER1, look at only the C_VOL and look at only b001 - nothing else. I have all these seperate components: the drive letter, the Server Name, the b00X number stored in array. How then can I go and use the Get-ChildItem with the -Include filter to only look at: .spi SERVER1 C_VOL b001 Given I have all of these separate components in an array taken from a text file: Get-Content .\PostBackupCheck-TextFile.txt | Select-Object -First $i { $a = $_ -split ' ' ; $locationArray += "$($a[0]):\$($a[1])\$($a[2])" ; $imageArray += "$($a[2])_$($a[3])_VOL_b00$($a[4])_i$($a[5]).spi" } I then go onto try and filter then and then get stuck: $latestIncremental = Get-ChildItem -Path ${shadowProtectDataLocation}\*.* -Include *.spi | Sort-Object LastAccessTime -Descending | Select-Object -First 1 I have the .spi filtered, but how can I also just include the C (for volume), the number for the b00x and the server name. Thanks!

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Java downcasting dilemma

- by Shades88

please have a look at this code here. class Vehicle { public void printSound() { System.out.print("vehicle"); } } class Car extends Vehicle { public void printSound() { System.out.print("car"); } } class Bike extends Vehicle{ public void printSound() { System.out.print("bike"); } } public class Test { public static void main(String[] args) { Vehicle v = new Car(); Bike b = (Bike)v; v.printSound(); b.printSound(); Object myObj = new String[]{"one", "two", "three"}; for (String s : (String[])myObj) System.out.print(s + "."); } } Executing this code will give ClassCastException saying inheritance.Car cannot be cast to inheritance.Bike. Now look at the line Object myObj = new String[]{"one", "two", "three"};. This line is same as Vehicle v = new Car(); right? In both lines we are assigning sub class object to super class reference variable. But downcasting String[]myObj is allowed but (Bike)v is not. Please help me understand what is going on around here.

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Adding defaults and indexes to a script/generate command in a Rails Template?

- by charliepark

I'm trying to set up a Rails Template that would allow for comprehensive set-up of a specific Rails app. Using Pratik Naik's overview (http://m.onkey.org/2008/12/4/rails-templates), I was able to set up a couple of scaffolds and models, with a line that looks something like this ... generate("scaffold", "post", "title:string", "body:string") I'm now trying to add in Delayed Jobs, which normally has a migration file that looks like this: create_table :delayed_jobs, :force => true do |table| table.integer :priority, :default => 0 # Allows some jobs to jump to the front of the queue table.integer :attempts, :default => 0 # Provides for retries, but still fail eventually. table.text :handler # YAML-encoded string of the object that will do work table.text :last_error # reason for last failure (See Note below) table.datetime :run_at # When to run. Could be Time.now for immediately, or sometime in the future. table.datetime :locked_at # Set when a client is working on this object table.datetime :failed_at # Set when all retries have failed (actually, by default, the record is deleted instead) table.string :locked_by # Who is working on this object (if locked) table.timestamps end So, what I'm trying to do with the Rails template, is to add in that :default = 0 into the master template file. I know that the rest of the template's command should look like this: generate("migration", "createDelayedJobs", "priority:integer", "attempts:integer", "handler:text", "last_error:text", "run_at:datetime", "locked_at:datetime", "failed_at:datetime", "locked_by:string") Where would I put (or, rather, what is the syntax to add) the :default values in that? And if I wanted to add an index, what's the best way to do that?

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Streaming content to JSF UI

- by Mark Lewis

Hello, I was quite happy with my JSF app which read the contents of MQ messages received and supplied them to the UI like this: <rich:panel> <snip> <rich:panelMenuItem label="mylabel" action="#{MyBacking.updateCurrent}"> <f:param name="current" value="mylog.log" /> </rich:panelMenuItem> </snip> </rich:panel> <rich:panel> <a4j:outputPanel ajaxRendered="true"> <rich:insert content="#{MyBacking.log}" highlight="groovy" /> </a4j:outputPanel> </rich:panel> and in MyBacking.java private String logFile = null; ... public String updateCurrent() { FacesContext context=FacesContext.getCurrentInstance(); setCurrent((String)context.getExternalContext().getRequestParameterMap().get("current")); setLog(getCurrent()); return null; } public void setLog(String log) { sendMsg(log); msgBody = receiveMsg(moreargs); logFile = msgBody; } public String getLog() { return logFile; } until the contents of one of the messages was too big and tomcat fell over. Obviously, I thought, I need to change the way it works so that I return some form of stream so that no one object grows so big that the container dies and the content returned by successive messages is streamed to the UI as it comes in. Am I right in thinking that I can replace the work I'm doing now on a String object with a BufferedOutputStream object ie no change to the JSF code and something like this changing at the back end: private BufferedOutputStream logFile = null; public void setLog(String log) { sendMsg(args); logFile = (BufferedOutputStream) receiveMsg(moreargs); } public String getLog() { return logFile; }

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JavaScript Module Pattern - What about using "return this"?

- by Rob

After doing some reading about the Module Pattern, I've seen a few ways of returning the properties which you want to be public. One of the most common ways is to declare your public properties and methods right inside of the "return" statement, apart from your private properties and methods. A similar way (the "Revealing" pattern) is to provide simply references to the properties and methods which you want to be public. Lastly, a third technique I saw was to create a new object inside your module function, to which you assign your new properties before returning said object. This was an interesting idea, but requires the creation of a new object. So I was thinking, why not just use "this.propertyName" to assign your public properties and methods, and finally use "return this" at the end? This way seems much simpler to me, as you can create private properties and methods with the usual "var" or "function" syntax, or use the "this.propertyName" syntax to declare your public methods. Here's the method I'm suggesting: (function() { var privateMethod = function () { alert('This is a private method.'); } this.publicMethod = function () { alert('This is a public method.'); } return this; })(); Are there any pros/cons to using the method above? What about the others?

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Change Vimeo Video using JQuery

- by Abs

Hello all, How can I change the ID of the embedded vimeo video? Here is the embed code for example: <object width="578" height="325"> <param name="allowfullscreen" value="true" /> <param name="allowscriptaccess" value="always" /> <param name="movie" value="http://vimeo.com/moogaloop.swf?clip_id=11527784& server=vimeo.com&show_title=1&show_byline=0&show_portrait=0&color=00ADEF&fullscreen=1" /> <embed src="http://vimeo.com/moogaloop.swf?clip_id=11527784& server=vimeo.com&show_title=1&show_byline=0&show_portrait=0& color=00ADEF&fullscreen=1" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" width="578" height="325"></embed></object> How can I change the clip_id in both the object value and the embed source using JQuery or just pure javascript? The effect this has is that it changes the video. I have tested this on Firefox, if this won't work on all browsers please let me know! Thanks all for any help

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problem with drag and drop for the winform using c#

- by karthik

I dont have the title bar in my winform, so i need to code drag and drop for the entire form. I am using the below code to do it, which works fine. I have two panels in my form, PanelA and PanelB. During the startup i show PanelA where the drag and drop works perfectly. Later when the user clicks the button in PannelA, i need to make PanelA visible false and show the PanelB My drag and drop is not working when the PanelB is loaded in form. Whats the problem here ? private void SerialPortScanner_MouseUp(object sender, MouseEventArgs e) { this.drag = false; } private void SerialPortScanner_MouseDown(object sender, MouseEventArgs e) { this.drag = true; this.start_point = new Point(e.X, e.Y); } private void SerialPortScanner_MouseMove(object sender, MouseEventArgs e) { if (this.drag) { Point p1 = new Point(e.X, e.Y); Point p2 = this.PointToScreen(p1); Point p3 = new Point(p2.X - this.start_point.X, p2.Y - this.start_point.Y); this.Location = p3; } }

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Javascript "Match" Function Not Returning Proper Results in Safari or IE (but yes in FF)

- by Jascha

Forgive me as this is a time sensitive issue and I will have to switch the site back in a few hours so the link will be bad... but: I am simply comparing two strings looking for a match with this function... I have an array of objects called linkArray and I need to match the .src of each object to a .src I send it (the src of the clicked image). if the the src of the image I clicked matches the src of an object in my array, I set a variable to the link string of that object and return true, letting my page know that the link is available. Now, this works great in FF. But not in any other browser and I can't figure out for the life of me why. I have set up a dialogue box to literally compare, by eye, the two strings that should at the very least throw the message "match". Can anyone see what I am missing here??? here is the link... http://7thart.com/Jewish-History-and-Culture/Jews-and-Baseball-An-American-Love-Story If you click any of the thumbnails on the left, you will activate the function. Again, I apologize as after a few hours I have to switch back to the original site and this link will be invalid. Thanks in advance for your help. (function below)... function matchLink(a){ for(var i=0;i<linkArray.length;i++){ var fixLink = '../' + linkArray[i]['src']; alert(fixLink + '\n = \n' + a); if(fixLink == a){ alert('match'); newLink = linkArray[i]['link']; return true; } } return false; } Note: The "match" will return on two of the images.. the initial image, and the first thumbnail on the left. The second thumbnail SHOULD match, and the third one SHOULD NOT match.

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getting a "default" concrete class that implements an interface

- by Roger Joys

I am implementing a custom (and generic) Json.net serializer and hit a bump in the road that I could use some help on. When the deserializer is mapping to a property that is an interface, how can I best determine what sort of object to construct to deserialize to to place into the interface property. I have the following: [JsonConverter(typeof(MyCustomSerializer<foo>))] class foo { int Int1 { get; set; } IList<string> StringList {get; set; } } My serializer properly serializes this object, and but when it comes back in, and I try to map the json parts to to object, I have a JArray and an interface. I am currently instantiating anything enumerable like List as theList = Activator.CreateInstance(property.PropertyType); This works create to work with in the deserialization process, but when the property is IList, I get runtime complaints (obviously) about not being able to instantiate an interface. So how would I know what type of concrete class to create in a case like this? Thank you

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Extracting function declarations from a PHP file

- by byronh

I'm looking to create an on-site API reference for my framework and application. Basically, say I have a class file model.class.php: class Model extends Object { ... code here ... // Separates results into pages. // Returns Paginator object. final public function paginate($perpage = 10) { ... more code here ... } } and I want to be able to generate a reference that my developers can refer to quickly in order to know which functions are available to be called. They only need to see the comments directly above each function and the declaration line. Something like this (similar to a C++ header file): // Separates results into pages. // Returns Paginator object. final public function paginate($perpage = 10); I've done some research and this answer looked pretty good (using Reflection classes), however, I'm not sure how I can keep the comments in. Any ideas? EDIT: Sorry, but I want to keep the current comment formatting. Myself and the people who are working on the code hate the verbosity associated with PHPDocumentor. Not to mention a comment-rewrite of the entire project would take years, so I want to preserve just the // comments in plaintext.

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How can I get type information at runtime from a DMP file in a Windbg extension?

- by pj4533

This is related to my previous question, regarding pulling objects from a dmp file. As I mentioned in the previous question, I can successfully pull object out of the dmp file by creating wrapper 'remote' objects. I have implemented several of these so far, and it seems to be working well. However I have run into a snag. In one case, a pointer is stored in a class, say of type 'SomeBaseClass', but that object is actually of the type 'SomeDerivedClass' which derives from 'SomeBaseClass'. For example it would be something like this: MyApplication!SomeObject +0x000 field1 : Ptr32 SomeBaseClass +0x004 field2 : Ptr32 SomeOtherClass +0x008 field3 : Ptr32 SomeOtherClass I need someway to find out what the ACTUAL type of 'field1' is. To be more specific, using example addresses: MyApplication!SomeObject +0x000 field1 : 0cae2e24 SomeBaseClass +0x004 field2 : 0x262c8d3c SomeOtherClass +0x008 field3 : 0x262c8d3c SomeOtherClass 0:000> dt SomeBaseClass 0cae2e24 MyApplication!SomeBaseClass +0x000 __VFN_table : 0x02de89e4 +0x038 basefield1 : (null) +0x03c basefield2 : 3 0:000> dt SomeDerivedClass 0cae2e24 MyApplication!SomeDerivedClass +0x000 __VFN_table : 0x02de89e4 +0x038 basefield1 : (null) +0x03c basefield2 : 3 +0x040 derivedfield1 : 357 +0x044 derivedfield2 : timecode_t When I am in WinDbg, I can do this: dt 0x02de89e4 And it will show the type: 0:000> dt 0x02de89e4 SomeDerivedClass::`vftable' Symbol not found. But how do get that inside an extension? Can I use SearchMemory() to look for 'SomeDerivedClass::`vftable'? If you follow my other question, I need this type information so I know what type of wrapper remote classes to create. I figure it might end up being some sort of case-statement, where I have to match a string to a type? I am ok with that, but I still don't know where I can get that string that represents the type of the object in question (ie SomeObject-field1 in the above example).

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How can I refactor this to work without breaking the pattern horribly?

- by SnOrfus

I've got a base class object that is used for filtering. It's a template method object that looks something like this. public class Filter { public void Process(User u, GeoRegion r, int countNeeded) { List<account> selected = this.Select(u, r, countNeeded); // 1 List<account> filtered = this.Filter(selected, u, r, countNeeded); // 2 if (filtered.Count > 0) { /* do businessy stuff */ } // 3 if (filtered.Count < countNeeded) this.SendToSuccessor(u, r, countNeeded - filtered) // 4 } } Select(...), Filter(...) are protected abstract methods and implemented by the derived classes. Select(...) finds objects in the based on x criteria, Filter(...) filters those selected further. If the remaining filtered collection has more than 1 object in it, we do some business stuff with it (unimportant to the problem here). SendToSuccessor(...) is called if there weren't enough objects found after filtering (it's a composite where the next class in succession will also be derived from Filter but have different filtering criteria) All has been ok, but now I'm building another set of filters, which I was going to subclass from this. The filters I'm building however would require different params and I don't want to just implement those methods and not use the params or just add to the param list the ones I need and have them not used in the existing filters. They still perform the same logical process though. I also don't want to complicated the consumer code for this (which looks like this) Filter f = new Filter1(); Filter f2 = new Filter2(); Filter f3 = new Filter3(); f.Sucessor = f2; f2.Sucessor = f3; /* and so on adding filters as successors to previous ones */ foreach (User u in users) { foreach (GeoRegion r in regions) { f.Process(u, r, ##); } } How should I go about it?

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How to specialize template for type derived from particular type

- by relaxxx

I have class World which manages creation of object... After creation it calls afterCreation method and I the created object is user-defined type derived from Entity (eg. MyEntity), I want to call addEntity. I the object was something else, I want to do nothing. addEntity must be called with appropriate T, because it generates unique IDs for every derived class etc. Here is my solution: template <int v> struct ToType { enum { value = v }; }; template <typename T> void World::afterCreation(T * t) { afterCreation(t, ToType<std::is_base_of<Entity, T>::value>()); } template <typename T> void World::afterCreation(T * t, ToType<true>) { addEntity(t); //here I cant pass Entity *, I need the real type, eg. MyEntity } template <typename T> void World::afterCreation(T * t, ToType<false>) { } My question is - Can in be done better way? How can I simulate following code without ToType or similar? template <typename T> void afterCreation(){/*generic impl*/} template <typename T where T is derived from Entity> void afterCreation(){/*some specific stuff*/} "specialize" in the title is only to describe my intention, no need to solve problem with template specialization

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jquery script that used to work is not working with jquery 1.4.2

- by Zayatzz

... and i cant figure out why. The script is following: <script type="text/javascript" src="http://path/to/js/jquery-1.4.2.min.js"></script> <script type="text/javascript"> function openMediaPlayer() { $('#flashMovie').animate({'height':'333px'}); } function closeMediaPlayer() { $('#flashMovie').animate({'height':'80px'}); } jQuery(function($){ $('#videoholder').bind('mouseenter', function(){ openMediaPlayer(); }); $('#videoholder').bind('mouseleave', function(){ closeMediaPlayer(); }); }); </script> <div id="videoholder" style="height:80px;width:412px;"> <object width="412" height="80" type="application/x-shockwave-flash" id="flashMovie" name="flashMovie" style="height: 80px;" data="http://path/to/Player.swf"><param name="menu" value="false"><param name="bgcolor" value="#666666"><param name="allowFullscreen" value="true"><param name="flashvars" value="playlistURL=http://path/to/Player/data/playlist.xml"></object> </div> pure and simple resizing flash object. It worked with older(1.3.2) jquery verision. The animate just does not work. Can anyone tell me what i should change to get it working again? Alan.

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How to mock a String using mockito?

- by Alceu Costa

I need to simulate a test scenario in which I call the getBytes() method of a String object and I get an UnsupportedEncodingException. I have tried to achieve that using the following code: String nonEncodedString = mock(String.class); when(nonEncodedString.getBytes(anyString())).thenThrow(new UnsupportedEncodingException("Parsing error.")); The problem is that when I run my test case I get a MockitoException that says that I can't mock a java.lang.String class. Is there a way to mock a String object using mockito or, alternatively, a way to make my String object throw an UnsupportedEncodingException when I call the getBytes method? Here are more details to illustrate the problem: This is the class that I want to test: public final class A{ public static String f(String str){ try{ return new String(str.getBytes("UTF-8")); } catch (UnsupportedEncodingException e) { // This is the catch block that I want to exercise. ... } } } This is my testing class (I'm using JUnit 4 and mockito): public class TestA { @Test(expected=UnsupportedEncodingException.class) public void test(){ String aString = mock(String.class); when(nonEncodedString.getBytes(anyString())).thenThrow(new UnsupportedEncodingException("Parsing error.")); A.f(aString); } }

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Get more error information from unhandled error

- by Andrew Simpson

I am using C# in a desktop application. I am calling a DLL written in C that I do not have the source code for. Whenever I call this DLL I get an untrapped error which I trap in an UnhandledException event/delegate. The error is : object reference not set to an instance of an object But the stack trace is empty. When I Googled this the info back was that the error was being hanlded eleswhere and then rethrown. But this can only be in the DLL I do not have the source code for. So, is there anyway I can get more info about this error? This is my code... in program.cs... AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException); static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e) { try { Exception _ex = (Exception)e.ExceptionObject; //the stact trace property is empty here.. } finally { Application.Exit(); } } My DLL... [DllImport("AutoSearchDevice.dll", EntryPoint = "Start", ExactSpelling = false, CallingConvention = CallingConvention.StdCall)] public static extern int Start(int ASD_HANDLE); An I call it like so: public static void AutoSearchStart() { try { Start(m_pASD); } catch (Exception ex) { } }

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ScaleTransform transforms non-linearly

- by Chris

I am using scale transform to allow a user to resize a control. What happens though is that when you start to move the mouse the control jumps to a new size, and then scales oddly. The further you move your mouse from the starting location the larger the increase in size becomes. I expect its the way I calculate the scale to be applied. Here is the code: private void ResizeGrip_MouseDown(object sender, MouseButtonEventArgs e) { ResizeHandle.CaptureMouse(); //Get the initial coordinate cursor location on the window initBtmX = e.GetPosition(this).X; bottomResize = true; } private void ResizeGrip_MouseUp(object sender, MouseButtonEventArgs e) { bottomResize = false; ResizeHandle.ReleaseMouseCapture(); } private void ResizeGrip_MouseMove(object sender, MouseEventArgs e) { if( bottomResize == true) { //Get the new Y coordinate cursor location double newBtmX = e.GetPosition(this).X; //Get the smallest change between the initial and new cursor location double diffX = initBtmX - newBtmX; // Let our rectangle capture the mouse ResizeHandle.CaptureMouse(); double newWidth = e.GetPosition(this).X - diffX; double scaler = newWidth / ResizeContainer.ActualWidth; Console.WriteLine("newWidth: {0}, scalar: {1}", newWidth, scaler); if (scaler < 0.75 || scaler > 3) return; ScaleTransform scale = new ScaleTransform(scaler, scaler); ResizeContainer.LayoutTransform = scale; } }

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Custom button with property as StaticResource

- by alin

I am trying to achieve the following thing: use an svg image into a custom button. In order to do this I created a Custom button: public class MainButton : Button { static MainButton() { DefaultStyleKeyProperty.OverrideMetadata(typeof(MainButton), new FrameworkPropertyMetadata(typeof(MainButton))); } public string Text { get { return (string)GetValue(TextProperty); } set { SetValue(TextProperty, value); } } public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(string), typeof(MainButton), new UIPropertyMetadata("")); public object Image { get { return (object)GetValue(ImageProperty); } set { SetValue(ImageProperty, value); } } public static readonly DependencyProperty ImageProperty = DependencyProperty.Register("Image", typeof(object), typeof(MainButton), new UIPropertyMetadata("")); } I took a svg file, opened it in inkscape and saved it as xaml file. I opened Themes.xaml and added the created xaml image as a ControlTemplate And the button style is: Style TargetType="{x:Type local:MainButton}" <StackPanel Canvas.Top="12" Canvas.Left="0" Canvas.ZIndex="2" Width="80"> <ContentControl x:Name="Img" Template="{StaticResource Home}" /> </StackPanel> <StackPanel x:Name="spText" Canvas.Top="45" Canvas.Left="1" Canvas.ZIndex="1" Width="80"> <TextBlock x:Name="Txt" Text="{Binding Path=(local:MainButton.Text), RelativeSource ={RelativeSource FindAncestor, AncestorType ={x:Type Button}}}" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="White" FontSize="14"/> </StackPanel> ... As you can see I have hardcoded the StaticResource name I want to be able to have a binding with property Image on this Template, something like So that I can set the Image property of the button with the name of the StaticResource I want. For example, having beside "Home" image, another one "Back" I would have two buttons in MainWindow declared like this: Any advice is kindly taken. Thank you for your time.

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define a closure as method from class

- by user272839

Hi, i'm trying to play with php5.3 and closure. I see here (Listing 7. Closure inside an object : http://www.ibm.com/developerworks/opensource/library/os-php-5.3new2/index.html) that it's possible to use $this in the callback function, but it's not. So I try to give $this as use variable : $self = $this; $foo = function() use($self) { //do something with $self } So to use the same example : class Dog { private $_name; protected $_color; public function __construct($name, $color) { $this->_name = $name; $this->_color = $color; } public function greet($greeting) { $self = $this; return function() use ($greeting, $self) { echo "$greeting, I am a {$self->_color} dog named {$self->_name}."; }; } } $dog = new Dog("Rover","red"); $dog->greet("Hello"); Output: Hello, I am a red dog named Rover. First of all this example does not print the string but return the function, but that's not my problem. Secondly I can't access to private or protected, because the callback function is a global function and not in the context from the Dog object. Tha't my problem. It's the same as : function greet($greeting, $object) { echo "$greeting, I am a {$self->_color} dog named {$self->_name}."; } And I want : public function greet($greeting) { echo "$greeting, I am a {$self->_color} dog named {$self->_name}."; } Which is from Dog and not global. I hope that I am clear ...

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java: retrieving the "canonical value" from a Set<T> where T has a custom equals()

- by Jason S

I have a class Foo which overrides equals() and hashCode() properly. I would like to also would like to use a HashSet<Foo> to keep track of "canonical values" e.g. I have a class that I would like to write like this, so that if I have two separate objects that are equivalent I can coalesce them into references to the same object: class Canonicalizer<T> { final private Set<T> values = new HashSet<T>(); public T findCanonicalValue(T value) { T canonical = this.values.get(value); if (canonical == null) { // not in the set, so put it there for the future this.values.add(value); return value; } else { return canonical; } } } except that Set doesn't have a "get" method that would return the actual value stored in the set, just the "contains" method that returns true or false. (I guess that it assumes that if you have an object that is equal to a separate object in the set, you don't need to retrieve the one in the set) Is there a convenient way to do this? The only other thing I can think of is to use a map and a list: class Canonicalizer<T> { // warning: neglects concurrency issues final private Map<T, Integer> valueIndex = new HashMap<T, Integer>(); final private List<T> values = new ArrayList<T>(); public T findCanonicalValue(T value) { Integer i = this.valueIndex.get(value); if (i == null) { // not in the set, so put it there for the future i = this.values.size(); this.values.add(value); this.valueIndex.put(value, i); return value; } else { // in the set return this.values.get(i); } } }

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How do actually castings work at the CLR level?

- by devoured elysium

When doing an upcast or downcast, what does really happen behind the scenes? I had the idea that when doing something as: string myString = "abc"; object myObject = myString; string myStringBack = (string)myObject; the cast in the last line would have as only purpose tell the compiler we are safe we are not doing anything wrong. So, I had the idea that actually no casting code would be embedded in the code itself. It seems I was wrong: .maxstack 1 .locals init ( [0] string myString, [1] object myObject, [2] string myStringBack) L_0000: nop L_0001: ldstr "abc" L_0006: stloc.0 L_0007: ldloc.0 L_0008: stloc.1 L_0009: ldloc.1 L_000a: castclass string L_000f: stloc.2 L_0010: ret Why does the CLR need something like castclass string? There are two possible implementations for a downcast: You require a castclass something. When you get to the line of code that does an castclass, the CLR tries to make the cast. But then, what would happen had I ommited the castclass string line and tried to run the code? You don't require a castclass. As all reference types have a similar internal structure, if you try to use a string on an Form instance, it will throw an exception of wrong usage (because it detects a Form is not a string or any of its subtypes). Also, is the following statamente from C# 4.0 in a Nutshell correct? Upcasting and downcasting between compatible reference types performs reference conversions: a new reference is created that points to the same object. Does it really create a new reference? I thought it'd be the same reference, only stored in a different type of variable. Thanks

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JSF2.0: variable list of custom component

- by rattaman

Hello Is there any way of using JSF2.0 in connection with variable lists of components? For example, lets say I have list o people that I would like to edit. They are presented on the page as list of components PersonEditor, which allow changing person data. Each editor is associated with single Person element. In order for this to work I need to perform following steps: On initial request: Get list of people For each person create PersonEditor and associate it with Person object. Fill editor's data. On user action: When user changes values and presses Save, data is processed by backing bean. I can either fill editor with data from list of people or bind it to the backing bean, but not at the same time, so I am stuck. I tried people.xhtml <ui:render value="#{bean.people}" var="person"> <example:personEditor person="#{person}"/> </ui:render> where personEditor.xhtml: a) proper association with person object, but no connection to backing bean <h:form> <h:outputText value="#{cc.attr.person.name}"/> <h:commandButton name="Save" actionListener="editorBean.save"> <f:ajax execute="@form" render="@form"/> </h:commandButton> </h:form> b) no association with person object, but there is connection to backing bean - there is no way to pass that person to the backing bean <h:form> <h:outputText value="#{editorBean.name}"/> <h:commandButton name="Save" actionListener="editorBean.save"> <f:ajax execute="@form" render="@form"/> </h:commandButton> </h:form> If I had each editor on separate page, I could pass the person id as url parameter (either using f:param or f:attribute) and initialize it accordingly. Is there any solution to this problem?

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How operator oveloading works

- by Rasmi Ranjan Nayak

I have below code class rectangle { ..... .....//Some code int operator+(rectangle r1) { return(r1.length+length); } }; In main fun. int main() { rectangle r1(10,20); rectangle r2(40,60); rectangle r3(30,60); int len = r1+r3; } Here if we will see in operator+(), we are doing r1.length + length. How the compiler comes to know that the 2nd length in return statement belong to object r3 not to r1 or r2? I think answer may be in main() we have writeen int len = r1+r3; If that is the case then why do we need to write in operator+(....) { r1.lenth + lenth; //Why not length + length? } Why not length + length? Bcause compiler already knows from main() that the first length belong to object r1 and 2nd to object r3.

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asp.net Can I force every page to inherit from a base page? Also should some of this logic be in my master page?

- by Bex

Hi! I have a web app that has a base page. Each page needs to inherit from this base page as it contains properties they all need as well as dealing with the login rights. My base page has some properties, eg: IsRole1, IsRole2, currentUserID, Role1Allowed, Role2Allowed. On the init of each page I set the properties "Role1Allowed" and "Role2Allowed" Private Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init Role1Allowed = True Role2Allowed= False End Sub The basepage then decides if the user needs redirecting. 'Sample code so not exactly what is going to be, bug gives the idea Protected Overridable Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) If Role1Allowed And Not Role1 Then 'Redirect somewhere End If End Sub The page then must override this pageload if they need anything else in it, but making sure they call the base pageload first. Protected Overrides Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load MyBase.Page_Load(sender, e) If Not IsPostBack Then BindGrid() End If End Sub The other properties (IsRole1, IsRole, currentUserID) are also accessible by the page so it can be decided if certain things need doing based on the user. (I hope this makes sense) Ok so I have 2 questions Should this functionality be in the base page or should it somehow be in the master, and if so how would I get access to all the properties if it was? As there are multiple people working on this project and creating pages some are forgetting to inherit from this basepage, or call the base pageload when overriding it. Is there any way to force them to do this? Thanks for any help. bex

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Obtaining FontMetrics before getting a Graphics instance

- by Tom Castle

Typically, I'd obtain a graphics instance something like this: BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB); Graphics2D g = img.createGraphics(); However, in the current project I'm working on, the width and height variables above are dependent upon the size of a number of text fragments that will later be drawn onto the graphics instance. But, to obtain the dimensions of the font being used I would usually use the FontMetrics that I get from the graphics object. FontMetrics metrics = g.getFontMetrics(); So, I have a nasty little dependency cycle. I cannot create the graphics object until I know the size of the text, and I cannot know the size of the text until I have a graphics object. One solution is just to create another BufferedImage/Graphics pair first in order to get the FontMetrics instance I need, but this seems unnecessary. So, is there a nicer way? Or is it the case that the width, height etc. properties for a Font are somehow dependent upon what (graphics, component...) the text is to be drawn on?

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