Entities tracking in Entity Framework

I started reading more about EF. I believed that entities are tracked as long as the context is in scope. But when I try the code below I get different results. I'm sure I misunderstood what I read. Can you please explain.

Destination canyon;
DbEntityEntry<Destination> entry;
using (var context = new BreakAwayContext())
      {
          canyon = (from d in context.Destinations.Include(d => d.Lodgings)
                    where d.Name == "Grand Canyon"
                    select d).Single();
          entry = context.Entry<Destination>(canyon);
      }
Console.WriteLine(entry.State); //Unchanged
canyon.TravelWarnings = "Carry enough water!";
Console.WriteLine(entry.State); //Modified

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Java3D move individual Point3f in shape3D consisting of big Point3f array

I have the following code that paints 4 points in a canvas3D window

public final class energon extends JPanel {    

    int s = 0, count = 0;

    public energon() {
        setLayout(new BorderLayout());
        GraphicsConfiguration gc=SimpleUniverse.getPreferredConfiguration();
        Canvas3D canvas3D = new Canvas3D(gc);//See the added gc? this is a preferred config
        add("Center", canvas3D);

        BranchGroup scene = createSceneGraph();
        scene.compile();

        // SimpleUniverse is a Convenience Utility class
        SimpleUniverse simpleU = new SimpleUniverse(canvas3D);


        // This moves the ViewPlatform back a bit so the
        // objects in the scene can be viewed.
        simpleU.getViewingPlatform().setNominalViewingTransform();

        simpleU.addBranchGraph(scene);
    }
    public BranchGroup createSceneGraph() {
        BranchGroup lineGroup = new BranchGroup();
        Appearance app = new Appearance();
        ColoringAttributes ca = new ColoringAttributes(new Color3f(204.0f, 204.0f,          204.0f), ColoringAttributes.SHADE_FLAT);
        app.setColoringAttributes(ca);

        Point3f[] plaPts = new Point3f[4];

        for (int i = 0; i < 2; i++) {
            for (int j = 0; j <2; j++) {
                plaPts[count] = new Point3f(i/10.0f,j/10.0f,0);
                //Look up line, i and j are divided by 10.0f to be able to
                //see the points inside the view screen
                count++;
            }
        }
        PointArray pla = new PointArray(4, GeometryArray.COORDINATES);
        pla.setCoordinates(0, plaPts);
        Shape3D plShape = new Shape3D(pla, app);
        TransformGroup objRotate = new TransformGroup();
        objRotate.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
        objRotate.addChild(plShape);
        lineGroup.addChild(objRotate);
        return lineGroup;
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.add(new JScrollPane(new energon()));
        frame.setSize(300, 300);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

Now i want to add a timertask that regularly updates the position of one of the points in the plaPts Point3f array. However, when i call plaPts[1].setX(2), nothing happens on the screen, they remain in the same position.

Do you have to have each point in a separate TransformGroup (consisting of a shape3D with a Point3f array of size 1) for this to be possible? I'm later going to use 100000 points, is it bad for performance if they all are in separate TransformGroups? Is there an easier way of doing this? Something like shape3D.repaint(), that automatically updates the position of the points based on the new values in plaPTS.

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Using scala.Future with Java 8 lambdas

The scala Future class has several methods that are based on functional programming. When called from Java, it looks like using lambdas from Java 8 would be a natural fit.

However, when I try to actually use that, I run into several problems. The following code does not compile

someScalaFuture.map(val -> Math.sqrt(val)).
       map(val -> val + 3); 

because map takes an ExecutionContext as an implicit argument. In Scala, you can (usually) ignore that, but it needs to be passed in explicitly in Java.

someScalaFuture.map(val -> Math.sqrt(val),
                    ec).
       map(val -> val + 3,
           ec);

This fails with this error:

error: method map in interface Future<T> cannot be applied to given types;
[ERROR] val),ExecutionContextExecutor
  reason: cannot infer type-variable(s) S
    (argument mismatch; Function1 is not a functional interface
      multiple non-overriding abstract methods found in interface Function1)
  where S,T are type-variables:
    S extends Object declared in method <S>map(Function1<T,S>,ExecutionContext)
    T extends Object declared in interface Future 

If I actually create an anonymous class extending Function1 and implement apply as such:

    someScalaFuture.map(new Function1<Double, Double>() {
            public double apply(double val) { return Math.sqrt(val); }
        },
        ec).
        map(val -> val + 3,
            ec);

I get an error that

error: <anonymous com.example.MyTestClass$1> is not abstract and does not override abstract method apply$mcVJ$sp(long) in Function1

I have not tried implementing that method (and am not sure if you can even implement a method with dollar signs in the middle of the name), but this looks like I am starting to wonder into the details of Scala implementations.

Am I going down a feasible path? Is there a reasonable way to use lambdas in this way? If there is a library that makes this work, that is an acceptable solution. Ideally, something like

import static org.thirdparty.MakeLambdasWork.wrap;
...
   wrap(someScalaFuture).map(val -> Math.sqrt(val)).
         map(val -> val + 3);

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Compose variadic template argument by transforming them

I have a simple situation which probably require a complex way to be solved but I'm unsure of it.

Basically I have this object which encapsulated a member function:

template<class T, typename R, typename... ARGS>
class MemberFunction
{
private:
  using function_type = R (T::*)(ARGS...);

  function_type function;

public:
  MemberFunction(function_type function) : function(function) { }

  void call(T* object, ARGS&&... args)
  {
    (object->*function)(args...);
  }   
};

This can be used easily

MemberFunction<Foo, int, int, int> function(&Foo::add)
Foo foo;
int res = function.call(&foo, 10,20)

The problem is that I would like to call it by passing through a custom environment which uses a stack of values to operate this method, this translates to the following code:

int arg2 = stack.pop().as<int>();
int arg1 = stack.pop().as<int>();
Foo* object = stack.pop().as<Foo*>();
int ret = function.call(object, arg1, arg2);
stack.push(Value(int));

This is easy to do directly in code but I'd like to find a way to encapsulate this behavior directly into MemberFunction class by exposing a single void call(Stack& stack) method which does the work for me to obtain something like:

MemberFunction<Foo, int, int, int> function(&Foo::add);
Stack stack;
stack.push(Value(new Foo());
stack.push(10);
stack.push(20);
function.call(stack);
assert(stack.pop().as<int>() == Foo{}.add(10,20));

But since I'm new to variadic templates I don't know how could I do in efficiently and elegantly.

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Navigating through Typescript references in Webstorm

We are using Typescript with Intellij Webstorm IDE.

The situation is we use ES6 import syntax and tsc compiler 1.5.3 (set as custom compiler in Webstorm also with flag --module commonjs)

The problem is it is imposible to click through (navigate to) method from module (file)

// app.ts

import * as myModule from 'myModule';

myModule.myFunction();



// myModule.ts

export function myFunction() {
    // implementation
}

When I click on .myFunction() in app.ts I expect to navigate to myModule.ts file but this doesn't happen?

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Why do I need a default contructor o Point class in this case?

I have this simple example of using a functor in C++:

#include <memory>
#include <ostream>
#include <iostream>

template <typename T>
struct Point {
    T x, y;

    Point(T x, T y) : x(x), y(y){};
    Point(){};

    Point<T> operator+(const Point<T>& other) {
        this->x += other.x;
        this->y += other.y;
        return *this;
    }
};

template <typename T>
struct AddSome {
    AddSome(){};
    AddSome(T* what) { add_what = (T)*what; };
    AddSome(T what) : add_what(what){};
    T operator()(T to_what) {
        if (ptr) {
            return to_what + add_what;
        }
        return to_what + add_what;
    };

   private:
    std::shared_ptr<T> ptr;
    T add_what;
};

int main(int argc, char* argv[]) {
    Point<int>* pt = new Point<int>(5, 6);

    AddSome<Point<int>> adder5(pt);
    Point<int> test = adder5(*pt);

    std::cout << test.x << " " << test.y << std::endl;

    return 0;
}

In the version above it works very well but it doesn't work at all if I delete the default constructor of the Point class.

What does the compiler need this constructor for?

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Indoor positioning System

I would like to develop an android app acting like an indoor positioning system.But I am stuck ,I don't know where to begin.I would like to know what is the best technology to use. I also want to know if there's a way to build this app based on BLE technology with beacons detection. Any information provided will be very helpful and thank you in advance.

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