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  • Flash: Closest point to MovieClip

    - by LiraNuna
    I need to constrain a point inside a DisplayObject given to me by the artist. I got it working but only for the occations where the cursor is still inside bounds. The limited object is called limited. function onSqMouseMove(event:MouseEvent) { if(bounds.hitTestPoint(event.stageX, event.stageY, true)) { limited.x = event.stageX; limited.y = event.stageY; } else { /* Find closest point in the Sprite */ } } limited.addEventListener(MouseEvent.MOUSE_DOWN, function(event:MouseEvent) { stage.addEventListener(MouseEvent.MOUSE_MOVE, onSqMouseMove); }); limited.addEventListener(MouseEvent.MOUSE_UP, function(event:MouseEvent) { stage.removeEventListener(MouseEvent.MOUSE_MOVE, onSqMouseMove); }); How do I go about implementing the other half of the function? I am aware Sprite's startDrag accepts arguments, where the second one is the constraint rectangle, but in my case, bounds are an arbitrary shape. When the object is dragged outside the bounds, I want to calculate the closest point from the cursor to bounds' polygon. Just to note that bounds can have 'holes'.

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  • Strict pointer aliasing: is access through a 'volatile' pointer/reference a solution?

    - by doublep
    On the heels of a specific problem, a self-answer and comments to it, I'd like to understand if it is a proper solution, workaround/hack or just plain wrong. Specifically, I rewrote code: T x = ...; if (*reinterpret_cast <int*> (&x) == 0) ... As: T x = ...; if (*reinterpret_cast <volatile int*> (&x) == 0) ... with a volatile qualifier to the pointer. Let's just assume that treating T as int in my situation makes sense. Does this accessing through a volatile reference solve pointer aliasing problem? For a reference, from specification: [ Note: volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation. See 1.9 for detailed semantics. In general, the semantics of volatile are intended to be the same in C++ as they are in C. — end note ] EDIT: The above code did solve my problem at least on GCC 4.5.

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  • Strange behaviour of CheckBox and TwoWay bound property

    - by walkor
    Hello, everyone. I fell in the following situation: I have a main UserControl with a DataGrid (which contains List). I need to show different panels depending on properties of the selected row(object). So i've created 2 controls and included them into this main control. Main control has 2 public properties - public List<ComplexObject> SourceList { get; set; } and public ComplexObject CurrentObject { get; set; } Pseudo-code: <UserControl x:Name="Main"> <DataGrid ItemsSource="{Binding SourceList}" SelectedItem="{Binding CurrentObject, Mode=TwoWay}"/> <Controls:RightPanelFirst Visibility="condition2"/> <Controls:RightPanelSecond Visibility="condition2"/> </UserControl> RightPanelFirst and RightPanelSecond have the following xaml: <UserControl> <... content here...> <CheckBox IsChecked="{Binding CurrentObject.ComplexProperty.SimpleProperty1, Mode=TwoWay}"> <CheckBox IsChecked="{Binding CurrentObject.ComplexProperty.SimpleProperty2, Mode=TwoWay}" x:Name="cbSecond"> <TextBox IsEnabled="{Binding IsChecked, ElementName=cbSecond}"/> </UserControl> So, my actual steps: Check both checkboxes (object values are set to true) Make other actions in code behind which modify CurrentObject. Then i want UI to reflect the changes, so I call NotifyPropertyChanged("CurrentObject"); SimpleProperty1 remains the same, but SimpleProperty2 resets to false I have no idea why this happens, can anyone help me please? Silverlight drives me mad.

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  • creating a thread in jsp and using join has problem

    - by Suresh S
    guys the following code does not wiat for the thread t to complete and join with the main thread, also the "created object" trace is called one more time after join is called please let me know the solution <% AProc empList = new AProc(); System.out.println("** Created Object ****"); System.out.println("Condition"+(!(p.length==0) && !(status) && !(threadLive))); if (!(p.length==0) && !(status) && !(threadLive)){ java.util.Date currDate = new java.util.Date(); try { Thread t = new Thread(empList); System.out.println("Check thread life 1 "+t.isAlive()); empList.setServletRequest(request , schemaName); System.out.println("Thread Started "+t); t.start(); System.out.println("Check thread life 2 "+t.isAlive()); if(t.isAlive()) { threadLive = true; } t.join(); while (t.isAlive()) { t.join(); } System.out.println("Check thread life 3 "+t.isAlive()); System.out.println("Thread End "+t); //} } catch (Exception e) { System.out.println("Exception in thread while running Procedure "+e); status=false; threadLive=false; } status = e.getStatusProc(); }%>

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  • Attaching methods to prototype from within constructor function

    - by Matthew Taylor
    Here is the textbook standard way of describing a 'class' or constructor function in JavaScript, straight from the Definitive Guide to JavaScript: function Rectangle(w,h) { this.width = w; this.height = h; } Rectangle.prototype.area = function() { return this.width * this.height; }; I don't like the dangling prototype manipulation here, so I was trying to think of a way to encapsulate the function definition for area inside the constructor. I came up with this, which I did not expect to work: function Rectangle(w,h) { this.width = w; this.height = h; this.constructor.prototype.area = function() { return this.width * this.height; }; } I didn't expect this to work because the this reference inside the area function should be pointing to the area function itself, so I wouldn't have access to width and height from this. But it turns out I do! var rect = new Rectangle(2,3); var area = rect.area(); // great scott! it is 6 Some further testing confirmed that the this reference inside the area function actually was a reference to the object under construction, not the area function itself. function Rectangle(w,h) { this.width = w; this.height = h; var me = this; this.constructor.prototype.whatever = function() { if (this === me) { alert ('this is not what you think');} }; } Turns out the alert pops up, and this is exactly the object under construction. So what is going on here? Why is this not the this I expect it to be?

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  • I want just the insert query for a temp table.

    - by John Stephen
    Hi..I am using C#.Net and Sql Server ( Windows Application ). I had created a temporary table. When a button is clicked, temporary table (#tmp_emp_details) is created. I am having another button called "insert Values" and also 5 textboxes. The values that are entered in the textbox are used and whenever com.ExecuteNonQuery(); line comes, it throws an error message Invalid object name '#tbl_emp_answer'.. Below is the set of code.. Please give me a solution. Code for insert (in insert value button): private void btninsertvalues_Click(object sender, EventArgs e) { username = txtusername.Text; examloginid = txtexamloginid.Text; question = txtquestion.Text; answer = txtanswer.Text; useranswer = txtanswer.Text; SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=tempdb;Integrated Security=True;"); SqlCommand com = new SqlCommand("Insert into #tbl_emp_answer values('"+username+"','"+examloginid+"','"+question+"','"+answer+"','"+useranswer+"')", con); con.Open(); com.ExecuteNonQuery(); con.Close(); }

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  • Fading in and fading out for a form

    - by karthik
    hi i have a requirement in which my form is transparent,if my mouse enters into it the form should became visible,if my mouse leaves out of the form it becomes transparent, i have three different controls placed in my form , each controls mouse leave and mouse enter is the same that of the form . if my mouse enters into the form and enters into a control form_mouseleaveevent and control_mouseenterd gets fired so iam not able to achieve it,how to overcome this. below is the piece of code for this: private void TransToOpac() { if (!isTransparent) return; if (TtoOON == false ) { TtoOON = true; for (i = this.Opacity; i <= 1; i = i + 0.02) { this.Opacity = i; Thread.Sleep(50); } isTransparent = false; TtoOON = false; } } private void OpacToTrans() { if (isTransparent) return; if (OtoTON == false ) { OtoTON = true; for (i = this.Opacity; i >= 0.5; i = i - 0.02) { this.Opacity = i; Thread.Sleep(50); } isTransparent = true; OtoTON = false; } } private void OnMouseEntered(object sender, EventArgs e) { TransToOpac(); } private void OnMouseLeft(object sender, EventArgs e) { OpacToTrans(); }

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  • How to add Remember me function at custom login box ?

    - by morningglory
    In my theme, there's custom page for the login. Login function at functions.php is like this function log_in($username, $password) { $user = parse_user($username); $username = $username; $password = $password; if(isEmptyString($username)) return new WP_Error('username', 'required'); if(isEmptyString($password)) return new WP_Error('password', "required"); if(!wp_check_password( $password, $user->user_pass ) ) return new WP_Error('wrong_password', "wrong"); wp_set_auth_cookie($user->ID, $remember); wp_login($username, $password); redirect_profile(); } function parse_user($info = null, $return = 'object') { if ( is_null( $info ) ) { global $current_user; if ( empty( $current_user->ID ) ) return null; $info = get_userdata( $current_user->ID ); } elseif ( empty( $info ) ) { return null; } if( $return == 'ID' ) { if ( is_object( $info ) ) return $info->ID; if ( is_numeric( $info ) ) return $info; } elseif( $return == 'object' ) { if ( is_object( $info ) && $info->ID) return $info; if ( is_object( $info )) return get_userdata( $info->ID ); if ( is_numeric( $info ) ) return get_userdata( $info ); if ( is_string( $info ) ) return get_userdatabylogin( $info ); } else { return null; } } I want to add remember me checkbox for user to logged in all the time until they logout. How can i add this ? Please kindly help me out. Thank you.

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  • Calling web service from seems to hang

    - by anothershrubery
    I am trying to call an asmx web service from an Android app. Just literally started some Android development today. I've been following various solutions I have found on the net and on here and it seems it is more difficult than anticipated. I have tried various solutions and using KSoap2 seems to be the easiest way to implement this, well it would be if I could get it working. I have the following code which works up until a point: private class CallWebService extends AsyncTask<Void, Void, Void> { private static final String SOAP_ACTION = "http://tempuri.org/GetUser"; private static final String METHOD_NAME = "GetUser"; private static final String NAMESPACE = "http://tempuri.org/"; private static final String URL = "http://160.10.1.79:59315/Service1.asmx"; TextView tv; @Override protected Void doInBackground(Void... params) { tv=(TextView)findViewById(R.id.txtMessage); try { SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); envelope.dotNet=true; envelope.setOutputSoapObject(request); HttpTransportSE androidHttpTransport = new HttpTransportSE(URL); androidHttpTransport.call(SOAP_ACTION, envelope); Object result = (Object)envelope.getResponse(); tv.setText(result.toString()); } catch (Exception e) { tv.setText(e.getMessage()); } return null; } } It seems to hang at the line androidHttpTransport.call(SOAP_ACTION, envelope); Any ideas why? Is this the correct approach? Should I be looking in another direction?

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  • Embed URL from variable in HTML file in Rails application

    - by TejasM
    hi, I have a doubt which might be silly for experience Rails developers. I am creating an application which is suppose to embed a video player with URL passed to it. So while displaying i.e in XXX.html.erb file i am writting below code. Now problem is @movie.trailer is my variable in ruby code which has URL value . I want the embedded video to load with URL given by this variable value. Any suggestion how am i suppose to place the value of Ruby variable(@movie.trailer) in part. <object width="425" height="344"> <param name="movie" value="<% @movie.trailer %>"> </param><param name="allowFullScreen" value="true"> </param><param name="allowscriptaccess" alue="always"> </param><embed src="<% @movie.trailer %>" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object> Note :- This code is working perfectly fine if i statically give value of URL. Please help

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  • Jquery drag /drop and clone

    - by Sajeev
    Hi I need to achive this .. I have a set of droppable items ( basically I am droping designs on a apparel ) and I am dropping a clone.. If I don't like the dropped object (designs) - I want to delete that by doing something like hidden . But I am unable to do that. Please help me.. here is the code var clone; $(document).ready(function(){ $(".items").draggable({helper: 'clone',cursor: 'hand'}); $(".droparea").droppable({ accept: ".items", hoverClass: 'dropareahover', tolerance: 'pointer', drop: function(ev, ui) { var dropElemId = ui.draggable.attr("id"); var dropElem = ui.draggable.html(); clone = $(dropElem).clone(); // clone it and hold onto the jquery object clone.id="newId"; clone.css("position", "absolute"); clone.css("top", ui.absolutePosition.top); clone.css("left", ui.absolutePosition.left); clone.draggable({ containment: 'parent' ,cursor: 'crosshair'}); $(this).append(clone); alert("done dragging "); /lets assume I have a delete button when I click that clone should dissapear so that I can drop another design - but the following code has no effect //and the item is still visible , how to make it dissapear ? $('#newId').css("visibility","hidden"); } }); });

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  • How to read an xs:any response using CXF Generated Client?

    - by mfcabrera
    Hi, When consuming a webserice with CXF 2.1.4 (the generated client) I am having problem getting the response based on the following XSD snippet in the WSDL. CXF Generates a List representing it, but when I execute the service, the response comes null. I used wireshark to what I was reciving and indeed the response XMl is coming as expected, but CXF just give me null object. Below the XSD of the response object. And <!--- chunk --> <s:element name="GestionSIIFResponse"> <s:complexType> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="GestionSIIFResult"> <s:complexType mixed="true"> <s:sequence> <s:any /> </s:sequence> </s:complexType> </s:element> </s:sequence> </s:complexType> </s:element> <!--- chunk --> And this is the response I am getting from the service: <soap:Body> <GestionSIIFResponse xmlns="http://tempuri.org/"> <GestionSIIFResult> <Siif xmlns=""> <Pagina>NUY001B</Pagina> <Exitos> <ExitoRep> <CodExito>SIL0082</CodExito> <DesExito>La transaccion se ha aplicado satisfactoriamente</DesExito> </ExitoRep> </Exitos> <InformacionCab/> <Repeticiones/> </Siif> </GestionSIIFResult> </GestionSIIFResponse>

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  • Which class should store the lookup table?

    - by max
    The world contains agents at different locations, with only a single agent at any location. Each agent knows where he's at, but I also need to quickly check if there's an agent at a given location. Hence, I also maintain a map from locations to agents. I have a problem deciding where this map belongs to: class World, class Agent (as a class attribute) or elsewhere. In the following I put the lookup table, agent_locations, in class World. But now agents have to call world.update_agent_location every time they move. This is very annoying; what if I decide later to track other things about the agents, apart from their locations - would I need to add calls back to the world object all across the Agent code? class World: def __init__(self, n_agents): # ... self.agents = {} self.agent_locations = {} for id in range(n_agents): x, y = self.find_location() agent = Agent(self,x,y) self.agents.append(agent) self.agent_locations[x,y] = agent def update_agent_location(self, agent, x, y): del self.agent_locations[agent.x, agent.y] self.agent_locations[x, y] = agent def update(self): # next step in the simulation for agent in self.agents: agent.update() # next step for this agent # ... class Agent: def __init__(self, world, x, y): self.world = world self.x, self.y = x, y def move(self, x1, y1): self.world.update_agent_location(self, x1, y1) self.x, self.y = x1, y1 def update(): # find a good location that is not occupied and move there for x, y in self.valid_locations(): if not self.location_is_good(x, y): continue if self.world.agent_locations[x, y]: # location occupied continue self.move(x, y) I can instead put agent_locations in class Agent as a class attribute. But that only works when I have a single World object. If I later decide to instantiate multiple World objects, the lookup tables would need to be world-specific. I am sure there's a better solution... EDIT: I added a few lines to the code to show how agent_locations is used. Note that it's only used from inside Agent objects, but I don't know if that would remain the case forever.

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  • How to display panel which is of Singleton class in two different frames at a time?

    - by Sriku
    I am trying to display a singleton obj on two different Jframe, but it is displayed only in the Jframe in which the object is added at last ( in example Frame2). Other Jframe is empty. This Singleton class is inherited from Panel and contains a label in it. Can anybody please tell me how can i display this singleton object in two different frame ? public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { NewJFrame inst = new NewJFrame(); inst.setTitle("Frame1"); inst.setSize(300, 300); inst.setLocationRelativeTo(null); inst.setVisible(true); singltonpanel _sin = singltonpanel.instance(); inst.add(_sin); inst.repaint(); JFrame frame = new JFrame("Frame2"); frame.setSize(300, 300); frame.setVisible(true); singltonpanel _sin1 = singltonpanel.instance(); frame.add(_sin1); frame.repaint(); } });

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  • CoreMidi _MIDINetworkNotificationContactsDidChange symbol not found

    - by Domestic Cat
    I'm getting the following error after a crash in an iPad app that uses CoreMIDI (The * are to blank out the app name): Dyld Error Message: Symbol not found: _MIDINetworkNotificationContactsDidChange Referenced from: /var/mobile/Applications/8F08B78E-929D-4C5A-9F02-08FD5743C17F/***.app/*** Expected in: /System/Library/Frameworks/CoreMIDI.framework/CoreMIDI in /var/mobile/Applications/8F08B78E-929D-4C5A-9F02-08FD5743C17F/***.app/*** Dyld Version: 179.4 When the app launches, I listen for MIDI Network Sessions using [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(sessionDidChange:) name:MIDINetworkNotificationSessionDidChange object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(sessionDidChange:) name:MIDINetworkNotificationContactsDidChange object:nil]; Which seems to be what is causing the crash. This is after I call session = [MIDINetworkSession defaultSession]; session.enabled = YES; session.connectionPolicy = MIDINetworkConnectionPolicy_Anyone; MIDIClientCreate(CFSTR("MidiManager"), midiNotifyProc, (void*)self, &midiClientRef); This kind of looks like CoreMIDI library has not been included in the build. Problem is, it IS included in the build as a required framework. (And the deployment target is set to 4.2). I can run the build fine on my iPad and have been testing extensively with other users' iPads also with no problems whatsoever. Also, this is an update to an existing app that has had several updates already with no problems. I just double checked my deployment build and the framework is definitely included, and I just installed that build onto my iPad (with a different provisioning profile from the store) and it works fine also. What could be happening? Could it be that Xcode just did a bad build for the one I sent to Apple, or am I missing something obvious? Could I change the MIDINetworkNotificationSessionDidChange notification symbol to a literal string (@"MIDINetworkNotificationSessionDidChange") to fix things for the mean time? Thanks for any help!

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  • Grails - Removing an item from a hasMany association List on data bind?

    - by ecrane
    Grails offers the ability to automatically create and bind domain objects to a hasMany List, as described in the grails user guide. So, for example, if my domain object "Author" has a List of many "Book" objects, I could create and bind these using the following markup (from the user guide): <g:textField name="books[0].title" value="the Stand" /> <g:textField name="books[1].title" value="the Shining" /> <g:textField name="books[2].title" value="Red Madder" /> In this case, if any of the books specified don't already exist, Grails will create them and set their titles appropriately. If there are already books in the specified indices, their titles will be updated and they will be saved. My question is: is there some easy way to tell Grails to remove one of those books from the 'books' association on data bind? The most obvious way to do this would be to omit the form element that corresponds to the domain instance you want to delete; unfortunately, this does not work, as per the user guide: Then Grails will automatically create a new instance for you at the defined position. If you "skipped" a few elements in the middle ... Then Grails will automatically create instances in between. I realize that a specific solution could be engineered as part of a command object, or as part of a particular controller- however, the need for this functionality appears repeatedly throughout my application, across multiple domain objects and for associations of many different types of objects. A general solution, therefore, would be ideal. Does anyone know if there is something like this included in Grails?

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  • What to pass parameters to start an workflow through WCF

    - by Rubens Farias
    It's possible to define some start values to an workflow using WorkflowInstance.CreateWorkflow, like this: using(WorkflowRuntime runtime = new WorkflowRuntime()) { Dictionary<string, object> parameters = new Dictionary<string, object>(); parameters.Add("First", "something"); parameters.Add("Second", 42); WorkflowInstance instance = runtime.CreateWorkflow(typeof(MyStateMachineWorkflow), parameters); instance.Start(); waitHandle.WaitOne(); } This way, a MyStateMachineWorkflow instance is created and First and Second public properties gets that dictionary values. But I'm using WCF; so far, I managed to create a Start method which accepts that two arguments and I set that required fields by using bind on my ReceiveActivity: using (WorkflowServiceHost host = new WorkflowServiceHost(typeof(MyStateMachineWorkflow))) { host.Open(); ChannelFactory<IMyStateMachineWorkflow> factory = new ChannelFactory<IMyStateMachineWorkflow>("MyStateMachineWorkflow"); IMyStateMachineWorkflow proxy = factory.CreateChannel(); // set this values through binding on my ReceiveActivity proxy.Start("something", 42); } While this works, that create an anomaly: that method should be called only and exactly once. How can I start an workflow instance through WCF passing those arguments? On my tests, I just actually interact with my workflow through wire after I call that proxy method. Is there other way?

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  • Can I get the item type from a BindingSource?

    - by Preston
    I would like to get the Type of item that a BindingSource is hooked up to or configured for. The BindingSource.DataSource property can be set to an object, list, or type. If it is a Type, it obviously does not have an bound item yet, but I would still like to get the Type. For a List, I need the item Type, not the list type. There is a method BindingSource.GetItemProperties, that accomplishes most of what I need. It gets the PropertyDescriptors for the Type, list item, or object specified by the DataSource and DataMember. The reason I ask, is that I have some components that I would like to re-use, but they are currently setup to work off of an item Type. The Type is mainly used to get PropertyInfos and then build a UI, but PropertyInfo and PropertyDescriptor is not exactly the same, so it is not immediately apparent that they can be reworked to use a PropertyDescriptor collection instead. Then there is cascading refactoring of everything already using these components and that adds up to a lot of work that I would rather not do. I've looked through the API docs for for a good way to do this, but so far I have not had any luck. Am I missing something or is this just something I can not or should not be doing?

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  • wpf treeview does not show child objects

    - by gangt
    I have an object with child object(s) and I load it using linq. And I assign it to a treeView's itemssource. treeView.DisplayMemberPath = "Name"; treeView.ItemsSource = tasks; It shows only the parent nodes (task.name), I couldn't figure out how to add children (TaskItems.name). All the examples show HierarchicalData in xaml. I need to do it in code-behind, just like the above code. Is it possible? public class Task { public int Id; public string Name; public bool IsActive; public List<TaskItem> TaskItems = new List<TaskItem>(); } public class TaskItem { public int TaskId; public string Name; public string Value; } -------------- var tasks1 = from t in xd.Descendants("taskheader") select new Task { Id = (int)t.Element("id"), Name = t.Element("name").Value, IsActive = t.Element("isactive").Value == "1", TaskItems = t.Elements("taskdetail").Select(e => new TaskItem { TaskId = (int)e.Element("taskid"), Name = (string)e.Element("name"), Value = (string)e.Element("value"), }).ToList() }; -------------- List<Task> tasks = new List<Task>(); tasks = tasks1;

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  • Imlpementations of an Interface with Different Types?

    - by b3njamin
    Searched as best I could but unfortunately I've learned nothing relevant; basically I'm trying to work around the following problem in C#... For example, I have three possible references (refA, refB, refC) and I need to load the correct one depending on a configuration option. So far however I can't see a way of doing it that doesn't require me to use the name of said referenced object all through the code (the referenced objects are provided, I can't change them). Hope the following code makes more sense: public ??? LoadedClass; public Init() { /* load the object, according to which version we need... */ if (Config.Version == "refA") { Namespace.refA LoadedClass = new refA(); } else if (Config.Version == "refB") { Namespace.refB LoadedClass = new refB(); } else if (Config.Version == "refC") { Namespace.refC LoadedClass = new refC(); } Run(); } private void Run(){ { LoadedClass.SomeProperty... LoadedClass.SomeMethod(){ etc... } } As you can see, I need the Loaded class to be public, so in my limited way I'm trying to change the type 'dynamically' as I load in which real class I want. Each of refA, refB and refC will implement the same properties and methods but with different names. Again, this is what I'm working with, not by my design. All that said, I tried to get my head around Interfaces (which sound like they're what I'm after) but I'm looking at them and seeing strict types - which makes sense to me, even if it's not useful to me. Any and all ideas and opinions are welcome and I'll clarify anything if necessary. Excuse any silly mistakes I've made in the terminology, I'm learning all this for the first time. I'm really enjoying working with an OOP language so far though - coming from PHP this stuff is blowing my mind :-)

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  • Protecting critical sections based on a condition in C#

    - by NAADEV
    Hello, I'm dealing with a courious scenario. I'm using EntityFramework to save (insert/update) into a SQL database in a multithreaded environment. The problem is i need to access database to see whether a register with a particular key has been already created in order to set a field value (executing) or it's new to set a different value (pending). Those registers are identified by a unique guid. I've solved this problem by setting a lock since i do know entity will not be present in any other process, in other words, i will not have same guid in different processes and it seems to be working fine. It looks something like that: static readonly object LockableObject = new object(); static void SaveElement(Entity e) { lock(LockableObject) { Entity e2 = Repository.FindByKey(e); if (e2 != null) { Repository.Insert(e2); } else { Repository.Update(e2); } } } But this implies when i have a huge ammount of requests to be saved, they will be queued. I wonder if there is something like that (please, take it just as an idea): static void SaveElement(Entity e) { (using ThisWouldBeAClassToProtectBasedOnACondition protector = new ThisWouldBeAClassToProtectBasedOnACondition(e => e.UniqueId) { Entity e2 = Repository.FindByKey(e); if (e2 != null) { Repository.Insert(e2); } else { Repository.Update(e2); } } } The idea would be having a kind of protection that protected based on a condition so each entity e would have its own lock based on e.UniqueId property. Any idea?

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  • Handling close-to-impossible collisions on should-be-unique values

    - by balpha
    There are many systems that depend on the uniqueness of some particular value. Anything that uses GUIDs comes to mind (eg. the Windows registry or other databases), but also things that create a hash from an object to identify it and thus need this hash to be unique. A hash table usually doesn't mind if two objects have the same hash because the hashing is just used to break down the objects into categories, so that on lookup, not all objects in the table, but only those objects in the same category (bucket) have to be compared for identity to the searched object. Other implementations however (seem to) depend on the uniqueness. My example (that's what lead me to asking this) is Mercurial's revision IDs. An entry on the Mercurial mailing list correctly states The odds of the changeset hash colliding by accident in your first billion commits is basically zero. But we will notice if it happens. And you'll get to be famous as the guy who broke SHA1 by accident. But even the tiniest probability doesn't mean impossible. Now, I don't want an explanation of why it's totally okay to rely on the uniqueness (this has been discussed here for example). This is very clear to me. Rather, I'd like to know (maybe by means of examples from your own work): Are there any best practices as to covering these improbable cases anyway? Should they be ignored, because it's more likely that particularly strong solar winds lead to faulty hard disk reads? Should they at least be tested for, if only to fail with a "I give up, you have done the impossible" message to the user? Or should even these cases get handled gracefully? For me, especially the following are interesting, although they are somewhat touchy-feely: If you don't handle these cases, what do you do against gut feelings that don't listen to probabilities? If you do handle them, how do you justify this work (to yourself and others), considering there are more probable cases you don't handle, like a supernonva?

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  • I don't like Python functions that take two or more iterables. Is it a good idea?

    - by Xavier Ho
    This question came from looking at this question on Stackoverflow. def fringe8((px, py), (x1, y1, x2, y2)): Personally, it's been one of my pet peeves to see a function that takes two arguments with fixed-number iterables (like a tuple) or two or more dictionaries (Like in the Shotgun API). It's just hard to use, because of all the verbosity and double-bracketed enclosures. Wouldn't this be better: >>> class Point(object): ... def __init__(self, x, y): ... self.x = x ... self.y = y ... >>> class Rect(object): ... def __init__(self, x1, y1, x2, y2): ... self.x1 = x1 ... self.y1 = y1 ... self.x2 = x2 ... self.y2 = y2 ... >>> def fringe8(point, rect): ... # ... ... >>> >>> point = Point(2, 2) >>> rect = Rect(1, 1, 3, 3) >>> >>> fringe8(point, rect) Is there a situation where taking two or more iterable arguments is justified? Obviously the standard itertools Python library needs that, but I can't see it being pretty in maintainable, flexible code design.

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  • Compound Primary Key in Hibernate using Annotations

    - by Rich
    Hi, I have a table which uses two columns to represent its primary key, a transaction id and then the sequence number. I tried what was recommended http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-mapping in section 2.2.3.2.2, but when I used the Hibernate session to commit this Entity object, it leaves out the TXN_ID field in the insert statement and only includes the BA_SEQ field! What's going wrong? Here's the related code excerpt: @Id @Column(name="TXN_ID") private long txn_id; public long getTxnId(){return txn_id;} public void setTxnId(long t){this.txn_id=t;} @Id @Column(name="BA_SEQ") private int seq; public int getSeq(){return seq;} public void setSeq(int s){this.seq=s;} And here are some log statements to show what exactly happens to fail: In createKeepTxnId of DAO base class: about to commit Transaction :: txn_id->90625 seq->0 ...<Snip>... Hibernate: insert into TBL (BA_ACCT_TXN_ID, BA_AUTH_SRVC_TXN_ID, BILL_SRVC_ID, BA_BILL_SRVC_TXN_ID, BA_CAUSE_TXN_ID, BA_CHANNEL, CUSTOMER_ID, BA_MERCHANT_FREETEXT, MERCHANT_ID, MERCHANT_PARENT_ID, MERCHANT_ROOT_ID, BA_MERCHANT_TXN_ID, BA_PRICE, BA_PRICE_CRNCY, BA_PROP_REQS, BA_PROP_VALS, BA_REFERENCE, RESERVED_1, RESERVED_2, RESERVED_3, SRVC_PROD_ID, BA_STATUS, BA_TAX_NAME, BA_TAX_RATE, BA_TIMESTAMP, BA_SEQ) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) [WARN] util.JDBCExceptionReporter SQL Error: 1400, SQLState: 23000 [ERROR] util.JDBCExceptionReporter ORA-01400: cannot insert NULL into ("SCHEMA"."TBL"."TXN_ID") The important thing to note is I print out the entity object which has a txn_id set, and then the following insert into statement does not include TXN_ID in the listing and thus the NOT NULL table constraint rejects the query.

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  • Questions regarding detouring by modifying the virtual table

    - by Elliott Darfink
    I've been practicing detours using the same approach as Microsoft Detours (replace the first five bytes with a jmp and an address). More recently I've been reading about detouring by modifying the virtual table. I would appreciate if someone could shed some light on the subject by mentioning a few pros and cons with this method compared to the one previously mentioned! I'd also like to ask about patched vtables and objects on the stack. Consider the following situation: // Class definition struct Foo { virtual void Call(void) { std::cout << "FooCall\n"; } }; // If it's GCC, 'this' is passed as the first parameter void MyCall(Foo * object) { std::cout << "MyCall\n"; } // In some function Foo * foo = new Foo; // Allocated on the heap Foo foo2; // Created on the stack // Arguments: void ** vtable, uint offset, void * replacement PatchVTable(*reinterpret_cast<void***>(foo), 0, MyCall); // Call the methods foo->Call(); // Outputs: 'MyCall' foo2.Call(); // Outputs: 'FooCall' In this case foo->Call() would end up calling MyCall(Foo * object) whilst foo2.Call() call the original function (i.e Foo::Call(void) method). This is because the compiler will try to decide any virtual calls during compile time if possible (correct me if I'm wrong). Does that mean it does not matter if you patch the virtual table or not, as long as you use objects on the stack (not heap allocated)?

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