I implemented my custom ArrayList using a resizeable Array, and I would like to unit test my add method to check if the right value getting inserted to the right position. My add method looks like this:
public class MyArrayList<T> implements ArrayListInterface {
private int max=20;
private int index = 0;
private int[] a = new int[max];
#Override
public void add(int value) {
if(index>max-1) {
resize();
}
a[index] = value;
index++;
}
I am aware, I could just make my method boolean and check what the method returns, but I would like to check that the right value added to the right position. My problem is that my Array is private, and that way it is only possible to reach its value through a getter. Is it a good solution to make a getter for my Array, and compare that to the actual result of the test, or what would be the best solution to test this method?
I have checked couple of other stackoverflow questions in the same topic, but I couldn't find any solution for my problem.
Add a get() (get(position), getLast(), etc.) method to your class and test using this method. Unit tests should exercise the class through its interfaces, without caring about the internal implementation. Any other class that will interact with your MyArrayList will do so through add() and get().
I'm seeing, more and more code like the code below in an MVVM application (WPF and Prism). Controllers have the following code fragments:
public class DispenseOptionController : IDispenseOptionController
{
protected readonly Func<IPharmacyCdmServiceSimpleClient> CdmClient;
protected readonly Func<IPatientServiceSimpleClient> PatientClient;
public DispenseOptionController(Func<IPharmacyCdmServiceSimpleClient> cdmClient, Func<IPatientServiceSimpleClient> patientClient)
{
CdmClient = cdmClient;
PatientClient = patientClient;
}...
I'm trying to understand the role that Func<> plays here. It seems that this delegate is used as parameters to the constructor. Can someone explain to me why anyone would use Func<> in this particular case? And can Func<> be replaced with anything else?
A Func<> is nothing but the Encapsulation of a method that one or more parameter and returns a value of the type specified by the TResult parameter.
You could see some use cases here
I was wondering how Mybatis get the private variable in Java.
For example:
Let's say we have a Java class called Foo:
public class Foo{
private int foolID;
public Foo(int foolID){
this.foolID = foolID;
}
}
And let's create XML mapper for insert.
<insert id="insert" parameterType="Foo">
insert into foo_table (id)
values (#{foolID});
</insert>
Let's say there are FooDAO java class and FooMapper java interface for this insert.
My question is how come foolID is readable even without Getter (Even if there is a getter method for foolID, I never specify what the getter is...). It seems like magic to me, and I know there is no magic for programming... :)
The only way I can think of is reflection.
Thanks for your help in advance.
That's correct, reflection is used to access private fields, but only if accessing private fields is not restricted.
Seams like reflection is used heavily not just to access private fields but to invoke setters getters etc.
I just tried to subscribe to WPF property change events using C++/CLI. I didn't expect this to get difficult.
First I tried to subscribe to a specific property of some window (IsMouseDirectlyOver) and finally succeeded with following code:
void MyClass::DependencyPropertyChanged(Object^ sender, DependencyPropertyChangedEventArgs args)
{
Debug::WriteLine("DependencyPropertyChanged: "+sender->ToString()+", "+args.Property->Name);
}
window->IsMouseDirectlyOverChanged += gcnew DependencyPropertyChangedEventHandler(this, &MyClass::DependencyPropertyChanged);
Then I tried to subscribe to any property changes of an object (which is most important to me because my final code must be able to handle property changes by property names). I totally failed on this.
I tried various things but nothing worked. I could not find any C++/CLI examples but according to documentation and C# examples the following seemed to be the most sensible code to me:
window->PropertyChanged += gcnew PropertyChangedEventHandler(this, &MyClass::PropertyChanged);
void MyClass::PropertyChanged(Object^ sender, PropertyChangedEventArgs^ args)
{
...
}
But the compiler tells me by error C2039 that 'PropertyChangedEvent' is no element of 'System::Windows::Window'.
How can I achieve what I want?
Al mentioned in the comments, your code doesn't work, because there is no PropertyChanged event on Window, it's as simple as that.
What you can do instead is to override the OnPropertyChanged() method, which is present on a Window. In your override, you can do anything you want, including raising PropertyChanged (don't forget to create that event first).
I had a look on the snoop sources. I modified it and wrote a very, very basic example that works:
String^ ownerPropertyName = "IsActive";
DependencyObject^ propertyOwner = window;
DependencyPropertyDescriptor^ ownerPropertyDescriptor = DependencyPropertyDescriptor::FromName(ownerPropertyName, propertyOwner->GetType(), propertyOwner->GetType());
DependencyProperty^ ownerProperty = ownerPropertyDescriptor->DependencyProperty;
Type^ ownerPropertyType = ownerProperty->PropertyType;
DependencyProperty^ myProperty = DependencyProperty::Register(ownerPropertyName, ownerPropertyType, GetType(), gcnew PropertyMetadata(gcnew PropertyChangedCallback(&MyClass::BoundPropertyChangedCallback)));
Binding^ myPropertyToOwnerPropertyBinding = gcnew Binding(ownerPropertyName);
myPropertyToOwnerPropertyBinding->Mode = BindingMode::OneWay;
myPropertyToOwnerPropertyBinding->Source = propertyOwner;
BindingOperations::SetBinding(this, myProperty, myPropertyToOwnerPropertyBinding);
And:
static void BoundPropertyChangedCallback(DependencyObject^ me, DependencyPropertyChangedEventArgs args)
{
Debug::WriteLine("BoundPropertyChangedCallback: "+args.OldValue+", "+args.NewValue+", "+args.Property->Name);
}
Looks pretty complicated to me. I have no idea if that binding stuff is really necessary. In fact this can even subscribe to properties that do not have events (like IsMouseOver) and can operate on objects that do not implement INotifyPropertyChanged (like Window). And it does not need any switch/case for properties.
The class PropertyDescriptor (or the derived DependencyPropertyDescriptor) provides a mechanism to add a property change handler by their AddValueChanged method:
DependencyPropertyDescriptor^ propertyDescriptor = DependencyPropertyDescriptor::FromName(
"ActualWidth", component->GetType(), component->GetType());
propertyDescriptor->AddValueChanged(component, gcnew EventHandler(ActualWidthChanged));
...
static void ActualWidthChanged(Object^ component, EventArgs^ e)
{
...
}
Unfortunately the handler doesn't get passed the changed property, so i guess you would have to add different handlers for all properties you want to monitor.
EDIT: You might implement something like the code shown below that uses an anonymous delegate to pass the property name to an appropriate handler. Note however that this is C#, and to my understanding this can't be done in C++/CLI, since there it does not support managed lambdas. Mayby you could wrap a helper class like this in a separate assembly and use it from your C++/CLI code.
public delegate void PropertyChangedHandler(object component, string propertyName);
public static class DependencyPropertyDescriptorExt
{
public static void AddPropertyChangedHandler(
this object component, string propertyName, PropertyChangedHandler handler)
{
var propertyDescriptor = DependencyPropertyDescriptor.FromName(
propertyName, component.GetType(), component.GetType());
propertyDescriptor.AddValueChanged(component, (o, e) => handler(o, propertyName));
}
}
Now you could write and use such a PropertyChangedHandler like this:
this.AddPropertyChangedHandler("ActualHeight", PropertyChanged);
...
private void PropertyChanged(object component, string propertyName)
{
...
}
I want to execute a static method from certain class in certain namespace, but I have a problem with using it as a method parameter.
Example:
Lets say there is a class:
namespace ExampleNamespace {
public ref class A
{
public:
static int MethodA();
};
}
And I want to use MethodA in other namespace as a other's method parameter:
MethodB(MethodA());
Only way I can make it work is by writing it like this:
ExampleNamespace::A^ a;
MethodB(a->MethodA());
Is there a way to write it without that 'a' declaration before?
Something like
MethodB(ExampleNamespace::A->MethodA())
wont work...
Thank you in advance.
MethodB(ExampleNamespace::A::MethodA());