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  • Great Circle & Ray intersection

    - by Karl T
    I have a Latitude, Longitude, and a direction of travel in degrees true north. I would like to calculate if I will intersect a line defined by two more Lat/Lon points. I figure the two points defining the line would create my great circle and my location and azimuth would define my ray (or possibly a small circle). Any ideas?

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  • UIScrollView content visible then bounces away

    - by Travis
    I have a pretty simple UIScrollView defined inside Interface Builder. I've pasted in some UILabels and when I run my app, I can drag to see the UILabels at the bottom but as soon as I let go it bounces away from view. What property controls this sort of setting?

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  • Elliptic Curve Diffie-Hellman

    - by cmaduro
    Does the Elliptic curve diffie hellman calculation look any different from the standard one defined here: /* * The basic Diffie-Hellman Key Agreement Equation * * The client initiates * A = g^a mod p * * Sends (g p A) to the server * * The server calculates B * B = g^b mod p * * Sends B back to client * * The client calculates K * K = B^a mod p * * The server calucaltes K * K = A^b mod p * */ Or is it just a specific way of selecting g, a, p and b? How are g,a,p and b selected anyway?

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  • Dependency Property Set Priority: CodeBehind vs. XAML

    - by LukePet
    When I initialize a control property from code, the binding to the same property defined on XAML don't work. Why? For Example, I set control properties on startup with this statements: myControl.SetValue(UIElement.VisibilityProperty, DefaultProp.Visibility); myControl.SetValue(UIElement.IsEnabledProperty, DefaultProp.IsEnabled); and on xaml I bind the property of myControl in this way: IsEnabled="{Binding Path=IsKeyControlEnabled}" now, when the property "IsKeyControlEnabled" changes to false, myControl remains enabled (because it's initialize with true value). How can I do?

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  • querying for timestamp field in django

    - by Hulk
    In my views i have the date in the following format s_date=20090106 and e_date=20100106 The model is defined as class Activity(models.Model): timestamp = models.DateTimeField(auto_now_add=True) how to query for the timestamp filed with the above info. Activity.objects.filter(timestamp>=s_date and timestamp<=e_date) Thanks.....

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  • Debugging T4 Template in VS 2010 Crashes IDE

    - by Eric J.
    I'm trying to debug a slightly-modified version of the ADO.NET POCO Entity Generator template using the directions Oleg Sych published a few years back. I modified the DbgJITDebugLaunchSetting key as recommended. I get a dialog indicating that a user-defined breakpoint has been hit. However, rather than being presented with the option to start a new instance of VS 2010 to debug, the original instance of VS 2010 just crashes and auto-restarts. Is it possible to debug T4 templates with VS 2010?

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  • include an APK in Android.mk

    - by ayden
    I'm writing a Android.mk to make a APK-A. and APK-A would use other classes defined in APK-B. I wonder that how should I wrote the Android.mk to include APK-B. Which tag should I use? Thanks.

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  • RCP applicatoon activities

    - by Peter
    I have a problem with my RCP application. First, I defined an activity in my plugin.xml: <extension point="org.eclipse.ui.activities"> <activity id="myproject.view.input.activity" name="myproject.view.input.activity"> <enabledWhen> <with variable="myproject.view.input.active"> <equals value="ENABLED"> </equals> </with> </enabledWhen> </activity> <activityPatternBinding activityId="myproject.view.input.activity" pattern="myproject.gui/myproject.view.input"> </activityPatternBinding> Then i defined my SourceProvider: <extension point="org.eclipse.ui.services"> <sourceProvider provider="myproject.util.CommandState"> <variable name="myproject.view.input.active" priorityLevel="workbench"> </variable> And, finally, my CommandState class: public class CommandState extends AbstractSourceProvider { public final static String OUTPUT_VIEW = "myproject.view.input.active"; // then goes some others variables, i just skip them // .... public final static String [] ACTIONS = {OUTPUT_VIEW /*and all others variables*/}; public final static String ENABLED = "ENABLED"; public final static String DISENABLED = "DISENABLED"; private final Map <String, String> currentState = new HashMap <String, String> (); @Override public void dispose() { } @Override public String[] getProvidedSourceNames() { return ACTIONS; } @Override public Map <String, String> getCurrentState() { return currentState; } public void setEnabled(boolean enabled, String [] commands) { String value = enabled ? ENABLED : DISENABLED; for (String command : commands) { currentState.put(command, value); fireSourceChanged(ISources.WORKBENCH, command, value); } } } In my Login window, application checks user permissions, and enable or disable views, commands, etc. with setEnabled method of CommandState. For commands it works fine, they are enabling or disabling correctly. But when i try to disable view and open perspective, that contains that view (myproject.view.input), it opened without that view, but also throws exception: !STACK 1 org.eclipse.ui.PartInitException: Could not create view: myproject.view.input at org.eclipse.ui.internal.ViewFactory.createView(ViewFactory.java:158) I can show full stacktrace if anyone want. I tried to debug my application and before i open my perspective whith that view, i checked currentState of my CommandState source provider, and all seemes to be ok: all variables values are correct and myproject.view.input.active = DISABLED Can anyone say, why exception is thrown? Thanks for any help. Sorry for big post and bad language

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  • How to create the new QTextDocument from existing widgets???

    - by Tom
    Hi, I'm absolutely confused with how to create the customized QTextDocument. I have the widget QWidget, which consists of some QLabels, QTableWidgets and QWidgets and I want to print it . I decided to create the new QTextDocument and insert in it all the defined widgets. I have already tried QTextCursor-insertBlock and insertText but my problem is how to define QTextBlockFormat or QTextCharFormat and say it, what is its "content", how to insert the widget in it. Can anyone help please? tom

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  • C#.Net Calling a C++ DLL

    - by hayer
    Hi I got a DLL(without the sourcecode) which exports like this: ?ReceiveCoreDataPtr@@YAXPAX@Z ?xenoAddRigidBodyAngularImpulse@@YAXHMMM@Z ?xenoAddRigidBodyForce@@YAXHMMM@Z ?xenoAddRigidBodyForce@@YAXHMMMMMM@Z ?xenoAddRigidBodyLinearImpulse@@YAXHMMM@Z ?xenoAddRigidBodyPointImpulse@@YAXHMMMMMM@Z ?xenoAddRigidBodyTorque@@YAXHMMM@Z ?xenoCharacterControllerCrouch@@YAXH@Z ?xenoCharacterControllerJump@@YAXH@Z ?xenoCharacterDisable@@YAXH@Z ?xenoCharacterEnable@@YAXH@Z ?xenoDeleteRigidBody@@YAXH@Z ?xenoEnd@@YAXXZ ?xenoGetCameraFOV@@YAKH@Z ?xenoGetCameraPointX@@YAKH@Z ?xenoGetCameraPointY@@YAKH@Z ?xenoGetCameraPointZ@@YAKH@Z ?xenoGetCameraPositionX@@YAKH@Z ?xenoGetCameraPositionY@@YAKH@Z ?xenoGetCameraPositionZ@@YAKH@Z ?xenoGetCharacterControllerHeadPosition@@YAKH@Z ?xenoGetCharacterControllerPositionX@@YAKH@Z ?xenoGetCharacterControllerPositionY@@YAKH@Z ?xenoGetCharacterControllerPositionZ@@YAKH@Z ?xenoGetCharacterControllerRotation@@YAKH@Z ?xenoGetRigidBodyAllowedPenetrationDepth@@YAKH@Z ?xenoGetRigidBodyAngularDamping@@YAKH@Z ?xenoGetRigidBodyAngularVelocityX@@YAKH@Z ?xenoGetRigidBodyAngularVelocityY@@YAKH@Z ?xenoGetRigidBodyAngularVelocityZ@@YAKH@Z ?xenoGetRigidBodyFriction@@YAKH@Z ?xenoGetRigidBodyGravityFactor@@YAKH@Z ?xenoGetRigidBodyLinearDamping@@YAKH@Z ?xenoGetRigidBodyLinearVelocityX@@YAKH@Z ?xenoGetRigidBodyLinearVelocityY@@YAKH@Z ?xenoGetRigidBodyLinearVelocityZ@@YAKH@Z ?xenoGetRigidBodyMass@@YAKH@Z ?xenoGetRigidBodyMaxAngularVelocity@@YAKH@Z ?xenoGetRigidBodyMaxLinearVelocity@@YAKH@Z ?xenoGetRigidBodyPointVelocityX@@YAKHMMM@Z ?xenoGetRigidBodyPointVelocityY@@YAKHMMM@Z ?xenoGetRigidBodyPointVelocityZ@@YAKHMMM@Z ?xenoGetRigidBodyRestitution@@YAKH@Z ?xenoIsRigidBodyALadder@@YAHH@Z ?xenoMakeCamera@@YAXHH@Z ?xenoMakeCharacterController@@YAXHMM@Z ?xenoMakeCharacterController@@YAXHMMM@Z ?xenoMakeCharacterController@@YAXHMMMM@Z ?xenoMakeCharacterController@@YAXHMMMMM@Z ?xenoMakeCharacterController@@YAXHMMMMMM@Z ?xenoMakeCharacterController@@YAXHMMMMMMM@Z ?xenoMakeRigidBodyDynamicBox@@YAXH@Z ?xenoMakeRigidBodyDynamicBox@@YAXHM@Z ?xenoMakeRigidBodyDynamicCapsule@@YAXH@Z ?xenoMakeRigidBodyDynamicCapsule@@YAXHM@Z ?xenoMakeRigidBodyDynamicCylinder@@YAXH@Z ?xenoMakeRigidBodyDynamicCylinder@@YAXHM@Z ?xenoMakeRigidBodyDynamicSphere@@YAXH@Z ?xenoMakeRigidBodyDynamicSphere@@YAXHM@Z ?xenoMakeRigidBodyStaticBox@@YAXH@Z ?xenoMakeRigidBodyStaticCapsule@@YAXH@Z ?xenoMakeRigidBodyStaticCylinder@@YAXH@Z ?xenoMakeRigidBodyStaticSphere@@YAXH@Z ?xenoMakeRigidBodyStaticTriangleMesh@@YAXH@Z ?xenoMakeVehicle@@YAXHH@Z ?xenoMoveCharacterControllerBackward@@YAXH@Z ?xenoMoveCharacterControllerForward@@YAXH@Z ?xenoMoveCharacterControllerLeft@@YAXH@Z ?xenoMoveCharacterControllerRight@@YAXH@Z ?xenoSetCharacterControllerPosition@@YAXHMMM@Z ?xenoSetCharacterControllerRotation@@YAXHM@Z ?xenoSetGravity@@YAXM@Z ?xenoSetGravity@@YAXMMM@Z ?xenoSetRigidBodyAllowedPenetrationDepth@@YAXHM@Z ?xenoSetRigidBodyAngularDamping@@YAXHM@Z ?xenoSetRigidBodyAngularVelocity@@YAXHMMM@Z ?xenoSetRigidBodyAsLadder@@YAXHH@Z ?xenoSetRigidBodyFriction@@YAXHM@Z ?xenoSetRigidBodyGravityFactor@@YAXHM@Z ?xenoSetRigidBodyLinearDamping@@YAXHM@Z ?xenoSetRigidBodyLinearVelocity@@YAXHMMM@Z ?xenoSetRigidBodyMass@@YAXHM@Z ?xenoSetRigidBodyMaxAngularVelocity@@YAXHM@Z ?xenoSetRigidBodyMaxLinearVelocity@@YAXHM@Z ?xenoSetRigidBodyPosition@@YAXHMMM@Z ?xenoSetRigidBodyRestitution@@YAXHM@Z ?xenoSetRigidBodyRotation@@YAXHMMM@Z ?xenoSetTimeStep@@YAXM@Z ?xenoStart@@YAXH@Z ?xenoStart@@YAXHM@Z ?xenoStart@@YAXHMH@Z ?xenoStart@@YAXXZ ?xenoUpdate@@YAXXZ ?xenoVehicleAccelerate@@YAXHM@Z ?xenoVehicleHandbrake@@YAXH@Z ?xenoVehicleReverse@@YAXH@Z ?xenoVehicleTurn@@YAXHM@Z When I try to use it in another C++ App like this #include <windows.h> class XenoPhysics { private: typedef void (*FunctionFunc)(void); typedef void (*FunctionFuncFloat)(float); typedef void (*FunctionFuncInt)(int); typedef void (*FunctionIntFloatFloatFloat)(int,float,float,float); HMODULE libInstance; public: void LoadLib() { this->libInstance = LoadLibrary(L"F:\\xenophysics.dll"); } void UnloadLib() { FreeLibrary(libInstance); } void xStart() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(this->libInstance, "?xenoStart@@YAXXZ"); curFunc(); } void xEnd() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "xenoEnd"); curFunc(); } void xUpdate() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "xenoUpdate"); curFunc(); } void xMakeRigidBodyStaticBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "xenoMakeRigidBodyStaticBox"); curFunc(objid); } void xMakeRigidBodyDynamicBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "xenoMakeRigidBodyDynamicBox"); curFunc(objid); } void xSetRigidBodyPosition(int objid, float x, float y, float z) { FunctionIntFloatFloatFloat curFunc; curFunc = (FunctionIntFloatFloatFloat)GetProcAddress(libInstance, "xenoSetRigidBodyPosition"); curFunc(objid, x, y, z); } void xSetGravity(float grav) { FunctionFuncFloat curFunc; curFunc = (FunctionFuncFloat)GetProcAddress(libInstance, "xenoSetGravity"); curFunc(grav); } }; This is the "wrapper"(or whatever you would call it) class.. To call the functions I'm doing XenoPhysics * d = new XenoPhysics(); d->LoadLib(); d->xStart(); It then throws the following error at me(Note that it passes the LoadLib() without any errors) Unhandled exception at 0x50261bc9 in Xeno Test.exe: 0xC0000005: Access violation reading location 0x00000064. And yes; I've checked that the "curFunc" gets the address, not just a NULL pointer(atleast I think I've checked that).. Anyone who can help out? Edit: Forgot the C#.Net code, how stupid of me :3 Here is the C++ CLR DLL "wrapper" I tried to make: #include <windows.h> // The following ifdef block is the standard way of creating macros which make exporting // from a DLL simpler. All files within this DLL are compiled with the XENOWRAPPERWIN32_EXPORTS // symbol defined on the command line. this symbol should not be defined on any project // that uses this DLL. This way any other project whose source files include this file see // XENOWRAPPERWIN32_API functions as being imported from a DLL, whereas this DLL sees symbols // defined with this macro as being exported. #ifdef XENOWRAPPERWIN32_EXPORTS #define XENOWRAPPERWIN32_API __declspec(dllexport) #else #define XENOWRAPPERWIN32_API __declspec(dllimport) #endif typedef void (*FunctionFunc)(); typedef void (*FunctionFuncFloat)(float); typedef void (*FunctionFuncInt)(int); typedef void (*FunctionIntFloatFloatFloat)(int,float,float,float); // This class is exported from the xeno wrapper win32.dll class XENOWRAPPERWIN32_API Cxenowrapperwin32 { public: Cxenowrapperwin32(void); HINSTANCE libInstance; // FunctionFunc curFunc; // Library base functions void LoadLib() { libInstance = LoadLibrary(L"F:\\xenophysics.dll"); } void UnloadLib() { FreeLibrary(libInstance); } // Function calls to the xeno physics void xStart() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "?xenoStart@@YAXXZ"); curFunc(); } void xEnd() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "?xenoEnd@@YAXXZ"); curFunc(); } void xUpdate() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "?xenoUpdate@@YAXXZ"); curFunc(); } void xMakeRigidBodyStaticBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "?xenoMakeRigidBodyStaticBox@@YAXH@Z"); curFunc(objid); } void xMakeRigidBodyDynamicBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "?xenoMakeRigidBodyDynamicBox@@YAXH@Z"); curFunc(objid); } void xSetRigidBodyPosition(int objid, float x, float y, float z) { FunctionIntFloatFloatFloat curFunc; curFunc = (FunctionIntFloatFloatFloat)GetProcAddress(libInstance, "?xenoSetRigidBodyPosition@@YAXHMMM@Z"); curFunc(objid, x, y, z); } void xSetGravity(float grav) { FunctionFuncFloat curFunc; curFunc = (FunctionFuncFloat)GetProcAddress(libInstance, "?xenoSetGravity@@YAXM@Z"); curFunc(grav); } }; extern XENOWRAPPERWIN32_API int nxenowrapperwin32; XENOWRAPPERWIN32_API int fnxenowrapperwin32(void); and here is how I use it in C#.Net class xeno { [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?LoadLib@Cxenowrapperwin32@@QAEXXZ")] public static extern void xLoadLib(); public void LoadLib() { xLoadLib(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?UnloadLib@Cxenowrapperwin32@@QAEXXZ")] public static extern void xUnloadLib(); public void UnloadLib() { xUnloadLib(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xStart@Cxenowrapperwin32@@QAEXXZ")] public static extern void xStart(); public void Start() { xStart(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xUpdate@Cxenowrapperwin32@@QAEXXZ")] public static extern void xUpdate(); public void Update() { xUpdate(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xEnd@Cxenowrapperwin32@@QAEXXZ")] public static extern void xEnd(); public void End() { xEnd(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xMakeRigidBodyDynamicBox@Cxenowrapperwin32@@QAEXH@Z")] public static extern void xMakeRigidBodyDynamicBox(int objid); public void MakeRigidBodyDynamicBox(int id) { xMakeRigidBodyDynamicBox(id); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xMakeRigidBodyStaticBox@Cxenowrapperwin32@@QAEXH@Z")] public static extern void xMakeRigidBodyStaticBox(int objid); public void MakeRigidBodyStaticBox(int id) { xMakeRigidBodyStaticBox(id); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xSetGravity@Cxenowrapperwin32@@QAEXM@Z")] public static extern void xSetGravity(float grav); public void SetGravity(float g) { xSetGravity(g); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xSetRigidBodyPosition@Cxenowrapperwin32@@QAEXHMMM@Z")] public static extern void xSetRigidBodyPosition(int obj, float x, float y, float z); public void SetRigidBodyPosition(int id, float q, float w, float e) { xSetRigidBodyPosition(id, q, w, e); } } And in the main C#.Net program I do xeno tx = new xeno(); tx.Start(); tx.SetGravity(-1); tx.MakeRigidBodyStaticBox(ground.Id); tx.MakeRigidBodyDynamicBox(cube.Id); tx.SetRigidBodyPosition(cube.Id, 0, 50, 0);

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  • When creating a WCF Service with NetTcpBinding, use endpoint "localhost" or machine's host name?

    - by Elan
    I have a WCF service that uses the NetTcpBinding and is running within a Windows service. Remote clients connect to this service. So far, I have defined the endpoint to use "localhost". If the host machine has multiple network adapters, will it receive messages on all adapters? Would it be better to assign the machine's host name to the endpoint instead of "localhost"? What are the advantages/disadvantages?

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  • Transmitting complex objects using TCP in C#

    - by Rakesh K
    Hi, I have a client server application in which I need to transmit a user defined object from Client to Server using TCP connection. My object is of the following structure: class Conversation { private string convName, convOwner; public ArrayList convUsers; public string getConvName() { return this.convName; } public string getConvOwner() { return this.convOwner; } } Please help me how to trnasmit this object at from client and again de-serialize it into appropriate object at server side. Thanks, Rakesh K.

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  • fake python modules via symlinks: on windows?

    - by eudoxos
    I have several compiled python modules; they are put into a single .so (to avoid runtime linking, there are cross-module symbol dependencies), but a number of symlinks points to this .so: libfoo.so -> liball.so libbar.so -> liball.so liball.so This way, I can do import foo (Python will call initfoo() defined in liball.so) or import bar (calls initbar()). I am wondering if this approach will work on Windows?

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  • log4j properties file: how to configure ?

    - by EugeneP
    Is it right that the procedure of using log4j looks like this: 1) put a .properties file somewhere in a project folder 2) in an initialization method, that runs only once, invoke PropertyConfigurator.configure("path_to_file"); 3) in every method we need to use logger we define a static logger variable and simply invoke getLogger(class) I'm asking you this: what if the initialization module is not defined? Where to put "log4j.properties" file so that we wouldn't need to invoke propertyconfigurator.configure at all, or if it's not possible, is it ok to invoke PropertyConfigurator.configure("path_to_file") in every method that uses a logger?

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  • Smarty html_options

    - by SeanJA
    For smarty's html_options function, is there a way to avoid having to do this (other than not using smarty that is)? {if $smarty.post} {html_options name=option_1 optins=$options selected=$smarty.post.option_1} {else} {html_options name=option_1 optins=$options} {/if} I realize that it won't show up in the template, but it seems like a bad practice to leave something that is not defined in the template (it also fills up my error logs with noise about undefined indexes).

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  • XPath find element based on ancestor element

    - by martymcfly
    Hi, again I have Java AST which is created from public class Test { String o = new String("hh"); public void wrong1() { synchronized(o) { // huhu } } } I try to create a XPath query which finds the synchronized block in which the defined String variable o is used. As the definition is above it is an ancestor of the SynchronizedStatement, but I dont get it working //SynchronizedStatement[Expression/PrimaryExpression/PrimaryPrefix/Name[@Image=ancestor::ClassOrInterfaceBody[ClassOrInterfaceBodyDeclaration/FieldVariableDeclaratorId/@Image]]] I know that /SynchronizedStatement[Expression/PrimaryExpression/PrimaryPrefix/Name[@Image= is correct, my problem is how to address the ancestor ClassOrInterfaceBody part. Hope its clear what i mean ;-) Thanks

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  • calling UIview methdods

    - by mindfreak
    I want to call this method in a user defined function (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation Is it possible ?? if yes,How ?? Pl. guide me.

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  • Partial overriding in Java (or dynamic overriding while overloading)

    - by Lie Ryan
    If I have a parent-child that defines some method .foo() like this: class Parent { public void foo(Parent arg) { System.out.println("foo in Function"); } } class Child extends Parent { public void foo(Child arg) { System.out.println("foo in ChildFunction"); } } When I called them like this: Child f = new Child(); Parent g = f; f.foo(new Parent()); f.foo(new Child()); g.foo(new Parent()); g.foo(new Child()); the output is: foo in Parent foo in Child foo in Parent foo in Parent But, I want this output: foo in Parent foo in Child foo in Parent foo in Child I have a Child class that extends Parent class. In the Child class, I want to "partially override" the Parent's foo(), that is, if the argument arg's type is Child then Child's foo() is called instead of Parent's foo(). That works Ok when I called f.foo(...) as a Child; but if I refer to it from its Parent alias like in g.foo(...) then the Parent's foo(..) get called irrespective of the type of arg. As I understand it, what I'm expecting doesn't happen because method overloading in Java is early binding (i.e. resolved statically at compile time) while method overriding is late binding (i.e. resolved dynamically at compile time) and since I defined a function with a technically different argument type, I'm technically overloading the Parent's class definition with a distinct definition, not overriding it. But what I want to do is conceptually "partially overriding" when .foo()'s argument is a subclass of the parent's foo()'s argument. I know I can define a bucket override foo(Parent arg) in Child that checks whether arg's actual type is Parent or Child and pass it properly, but if I have twenty Child, that would be lots of duplication of type-unsafe code. In my actual code, Parent is an abstract class named "Function" that simply throws NotImplementedException(). The children includes "Polynomial", "Logarithmic", etc and .foo() includes things like Child.add(Child), Child.intersectionsWith(Child), etc. Not all combination of Child.foo(OtherChild) are solvable and in fact not even all Child.foo(Child) is solvable. So I'm best left with defining everything undefined (i.e. throwing NotImplementedException) then defines only those that can be defined. So the question is: Is there any way to override only part the parent's foo()? Or is there a better way to do what I want to do?

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  • How to get the last element by date of each "type" in LINQ or TSQL

    - by Mauro
    Imagine to have a table defined as CREATE TABLE [dbo].[Price]( [ID] [int] NOT NULL, [StartDate] [datetime] NOT NULL, [Price] [int] NOT NULL ) where ID is the identifier of an action having a certain Price. This price can be updated if necessary by adding a new line with the same ID, different Price, and a more recent date. So with a set of a data like ID StartDate Price 1 01/01/2009 10 1 01/01/2010 20 2 01/01/2009 10 2 01/01/2010 20 How to obtain a set like the following? 1 01/01/2010 20 2 01/01/2010 20

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  • Objective-C categories in static library

    - by Vladimir
    Can you guide me how to properly link static library to iphone project. I use staic library project added to app project as direct dependency (target - general - direct dependecies) and all works OK, but categories. A category defined in static library is not working in app. So my question is how to add static library with some categories into other project? And in general, what is best practice to use in app project code from other projects?

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