[API Proposal]: ICommand.Null
Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 35/100
Research direction
Start by reviewing the proposed System.Windows.Input.ICommand API and the existing Stream.Null and TextWriter.Null patterns. Check how ICommand is provided by System.ObjectModel.dll and whether the proposed static member and nested implementation fit the project’s API review requirements; done means an approved design with its implementation and validation plan.
Written by the indexing model from the issue text.
Description
Background and motivation
For abstractions like ICommand it's useful to have a standard implementation that does nothing. We have some of them already, such as Stream.Null and TextWriter.Null.
API Proposal
namespace System.Windows.Input;
public partial interface ICommand
{
public static ICommand Null { get; } = new NullCommand();
private sealed class NullCommand : ICommand
{
public event EventHandler? CanExecuteChanged
{
add {}
remove {}
}
public bool CanExecute(object? parameter)
{
return true;
}
public void Execute(object? parameter)
{
// Do nothing
}
}
}
API Usage
private ICommand _command = ICommand.Null; // Might be set to something meaningful later
Alternative Designs
We could put it on a class instead, but we don't have a built-in implementation of ICommand in System.ObjectModel.dll, so I don't believe there is a good candidate. We could, of course, create one.
Risks
No response
- Dominant language
- C#
- Stars
- 18.3k
- Forks
- 5.6k
- PR merge metrics
- PR metrics pending
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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