Accommodate WinUI 2/3 dependencies per-experiment

[Arlodotexe]

Background

So far, Labs is set up to work with

• UWP - WinUI 2 (Windows)
• WinAppSDK - WinUI 3 (Windows)
• Uno Platform (WinUI 2 AND 3, all other platforms)

The problem

While devs can easily add nuget packages to the library code for their experiment, it's not currently possible to add nuget packages that work under Uno and accommodate both WinUI 2 and 3.

The cause

Under everything except UWP and WinAppSDK, the projects share a target framework between WinUI 2 and 3.

Possible solutions

We fixed this for labs itself in #75 by using a powershell script. The script UseUnoWinUI.ps1 modified the Labs.Uno.props file to switch between the WinUI 2 and WinUI 3 versions of the Uno packages, then suppresses git changes to prevent the user from changing the default for everyone else.

Doing this exact same setup for experiment dependencies would quickly get a mess due to the user changing the file + git suppressing changes.

Instead, we should try something like this:

    Experiment.Lib.csproj
              | Imports
              v
         Deps.props                   - Swap WinUI 2/3 import via pwsh, suppress git changes
              | 
             /\
           /    \
          |      | Imports
          v      v
WinUI2.props    WinUI3.props          - Allow user to freely modify

Then, in the UseUnoWinUI.ps1 script, in addition to modifying Labs.Uno.props, it would check each experiment and modify the Deps.props file to swap between importing WinUI2.props and WinUI3.props.

The ProjectTemplate will need to be adjusted for this, as well as all existing experiments.

Final note - pick better file names than the provided ones. They're shortened to fit in the graphic.

[michael-hawker]

Would these specific props files be part of each experiment or something we have all-up? As ideally, only each experiment's packages include whatever dependencies they need to work.

We also have to account for differences across Uno for both sides as well, no?

I do like the idea that we have two places to specify UWP + Uno dependencies vs. WinUI 3 + Uno dependencies and handle swapping that with the other script (as that's what controls that and in the CI).

As once it's setup a developer shouldn't have to worry about it.

I just want to make sure we make it accessible and straight-forward for folks to understand where they need to add dependencies and how (as their instinct is going to be right-click on the experiment library and 'manage nuget packages').

[Arlodotexe]

Would these specific props files be part of each experiment or something we have all-up? As ideally, only each experiment's packages include whatever dependencies they need to work.

These props files would be part of each experiment.

We also have to account for differences across Uno for both sides as well, no?

I'm not sure I understand the question.

I just want to make sure we make it accessible and straight-forward for folks to understand where they need to add dependencies and how (as their instinct is going to be right-click on the experiment library and 'manage nuget packages').

The Nuget Package Manager should work just fine for most cases. Dealing with the props files should only happen when you need to add an Uno-compatible UI library. Something to point out in docs, similar to how Uno does for the Community Toolkit.

[michael-hawker]

Related to #24 as well.