Naming user controls without default constructors in XAML

问题

I have a user control without a parameterless constructor; let's call it WithoutDefaultConstructor. I want to insert a WithoutDefaultConstructor called myControl into the XAML code of another control (which is called MainWindow). However, I get this compiler error:

The type 'WithoutDefaultConstructor' cannot have a Name attribute. Value types and types without a default constructor can be used as items within a ResourceDictionary.

How do I fix this without adding a parameterless constructor to WithoutDefaultConstructor?

Here are the contents of MainWindow.xaml:

<Window x:Class="WpfApplication1.MainWindow"
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 xmlns:WpfApplication1="clr-namespace:WpfApplication1" Title="MainWindow" 
 Height="350" Width="525">
    <WpfApplication1:WithoutDefaultConstructor Name="myControl">
    </WpfApplication1:WithoutDefaultConstructor>
</Window>

Here are the contents of WithoutDefaultConstructor.xaml.cs:

using System.Windows.Controls;

namespace WpfApplication1
{
    public partial class WithoutDefaultConstructor : UserControl
    {
        private int I_really_need_to_initialize_this_int;

        public WithoutDefaultConstructor(int i)
        {
            InitializeComponent();
            I_really_need_to_initialize_this_int = i;
        }
    }
}

回答1:

It's not about the Name attribute. You just can't create an instance of an object using constructor with parameter from XAML. There is a way to do it in XAML 2009, but it's not available in code compiled to BAML, such as this.

回答2:

Just don't do it. Instead, expose an int property on your user control. If you really want to make sure it's explicitly set, expose an int? and throw if it's null.

来源：https://stackoverflow.com/questions/6156924/naming-user-controls-without-default-constructors-in-xaml

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xaml

default-constructor