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While using WPF I noticed that when I add a control to a XAML file, the default constructor is called.
Is there a way to call a parameterized constructor?
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Example of Parameterized Constructor For example, when we create the object like this MyClass obj = new MyClass(123, "Hi"); then the new keyword invokes the Parameterized constructor with int and string parameters (MyClass(int, String)) after object creation.
It becomes a possible situation to pass arguments to that object. To create a parameterized constructor, it is needed to just add parameters as a value to the object as the way we pass a value to a function. Somewhat similar scenario we do by passing the parametrized values to the object created with the class.
Parameterized Constructor – A constructor is called Parameterized Constructor when it accepts a specific number of parameters. To initialize data members of a class with distinct values. In the above example, we are passing a string and an integer to the object.
A default constructor is a constructor that either has no parameters, or if it has parameters, all the parameters have default values. If no user-defined constructor exists for a class A and one is needed, the compiler implicitly declares a default parameterless constructor A::A() .
.NET 4.0 brings a new feature that challenges the answer - but apparently only for UWP applications (not WPF).
x:Arguments Directive
<object ...> <x:Arguments> oneOrMoreObjectElements </x:Arguments> </object> One of the guiding principles of XAML-friendly objects is that they should be completely usable with a default constructor, i.e., there is no behavior that is only accessible when using a non-default constructor. To fit with the declarative nature of XAML, object parameters are specified via property setters. There is also a convention that says that the order in which properties are set in XAML should not be important.
You may, however, have some special considerations that are important to your implementation but at odds with convention:
StreamSource and UriSource of an image.To make it easier to handle these cases, the ISupportInitialize interface is provided. When an object is read and created from XAML (i.e., parsed), objects implementing ISupportInitialize will be handled specially:
BeginInit() will be called.EndInit() is called.By tracking calls to BeginInit() and EndInit(), you can handle whatever rules you need to impose, including the requirement that certain properties be set. This is how you should handle creation parameters; not by requiring constructor arguments.
Note that ISupportInitializeNotification is also provided, which extends the above interface by adding an IsInitialized property and Initialized event. I recommend using the extended version.
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