Why don't avalonia save DataTemplate as a .DataTemplate file?

[jyswjjgdwtdtj]

If i can save a DataTemplate like <DataTemplate>......</DataTemplate> as a file (or style, or flyout, or other things), i can use it by

<ContentControl Content="xxx">
<ContentControl.ContentTemplate>
<dataTemplate:MyDataTemplate/>
</ContentControl.ContentTemplate>
</ContentControl>

It's more easier, more clear, and can be located directly where something goes wrong.
Now axaml parts should be saved in resource, and resource should be attached to app.axaml. I can't use the DataTemplate defined in A project in B project. And can not create instance of a DataTemplate in code.

[stevemonaco]

This is already possible. Most (any?) types you define in an Avalonia project can have a XAML file if you simply create a matching .xaml file with a matching x:Class though it's rarely useful.

MyDataTemplate.axaml.cs

using Avalonia.Markup.Xaml.Templates;

namespace AvaloniaSandbox.Shell;
public class MyDataTemplate : DataTemplate { }

MyDataTemplate.axaml

<DataTemplate
    x:Class="AvaloniaSandbox.Shell.MyDataTemplate"
    x:DataType="vm:MainWindowViewModel"
    xmlns="https://github.com/avaloniaui"
    xmlns:vm="using:AvaloniaSandbox.ViewModels"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <TextBlock Text="{Binding Text}" />
</DataTemplate>

Usage :

<ContentControl Content="{Binding}">
    <ContentControl.ContentTemplate>
        <local:MyDataTemplate />
    </ContentControl.ContentTemplate>
</ContentControl>

Note that this will display the value of MainWindowViewModel.Text. It is a pain to have empty class definitions, but I guess that's the price you pay. The team otherwise would probably need to create a new version of StyleInclude / ResourceInclude that also fits into the compile-time and runtime XAML tooling.