NuExt.Minimal.Mvvm.Legacy 0.7.3

NuExt.Minimal.Mvvm.Legacy

Legacy‑only add‑on for NuExt.Minimal.Mvvm targeting .NET Framework 4.6.2+ and .NET Standard 2.0.
It provides backports that are available on modern .NET in the base package.

This package is not deprecated code. It exists to support older TFMs.
Modern .NET (.NET 5+/netstandard2.1) does not use this package (no compatible assets).

Included backports

• AsyncValueCommand / AsyncValueCommand<T> — ValueTask-based async commands (backport of the modern feature available in NuExt.Minimal.Mvvm on .NET 5+/netstandard2.1).

Compatibility & Dependencies

• Targets: net462, netstandard2.0.
• Dependency: System.Threading.Tasks.Extensions (provides ValueTask on legacy TFMs).
  This dependency is not added on modern TFMs because the package exposes no assets there.

Installation

Add both the base package and the legacy add‑on to your legacy project:

dotnet add package NuExt.Minimal.Mvvm
dotnet add package NuExt.Minimal.Mvvm.Legacy

That’s it — AsyncValueCommand* become available on legacy targets.

Multi‑TFM projects: reference both packages.

• On modern TFMs, NuExt.Minimal.Mvvm provides AsyncValueCommand*; the legacy package is ignored (no assets).
• On legacy TFMs, this package provides AsyncValueCommand*; the base package does not include them there.

Example

public sealed class ValidateViewModel : ViewModelBase
{
    public IAsyncCommand ValidateCommand { get; }

    public ValidateViewModel()
    {
        ValidateCommand = new AsyncValueCommand(ValidateAsync);
    }

    private ValueTask ValidateAsync(CancellationToken ct)
    {
        if (IsValidFast()) return ValueTask.CompletedTask;
        return SlowValidateAsync(ct);
    }

    private bool IsValidFast() => /* lightweight checks */;
    private async ValueTask SlowValidateAsync(CancellationToken ct)
    {
        await Task.Delay(50, ct);
        // heavy checks...
    }
}

Notes

If you consume the .Sources of the base package on legacy and prefer not to use this add‑on, you can opt‑in manually by adding:

<PropertyGroup>
  <DefineConstants>$(DefineConstants);NUEXT_ENABLE_VALUETASK</DefineConstants>
</PropertyGroup>
<ItemGroup>
  <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.6.3" />
</ItemGroup>

• Do not combine .Sources opt‑in and this legacy package on the same legacy TFM to avoid duplicate type definitions.

License

MIT. See LICENSE.