Add/Remove params modifier refactoring

This refactoring allows you to improve APIs by introducing the params modifier to the last parameter of a collection type.

Consider an example of an API that accepts the array of types as the last argument:

        
public sealed class AcceptsDataAttribute : Attribute
{
    public AcceptsDataAttribute(string description, Type[] types) { }
}

Such API will force the consumers to construct arrays at the call site:

        
public class MyService
{
    [AcceptsData("Flag/text", new[] { typeof(string), typeof(bool) })]
    public void EntryPoint(object data)
    {
        // do something
    }
}

    

With this refactoring, you can improve this API ergonomics by adding the params modifier for Type[] types parameter and updating all usages.

            
public sealed class AcceptsDataAttribute : Attribute
{
    public AcceptsDataAttribute(string info, Type[] types) { }
}

public class MyService
{
    [AcceptsData("Flag/text", new[] { typeof(string), typeof(bool) })]
    public void EntryPoint(object data)
    {
        // do something
    }
}

        

            
public sealed class AcceptsDataAttribute : Attribute
{
    public AcceptsDataAttribute(string info, params Type[] types) { }
}

public class MyService
{
    [AcceptsData("Flag/text", typeof(string), typeof(bool))]
    public void EntryPoint(object data)
    {
        // do something
    }
}

        

Add 'params' modifier

Set the caret anywhere within the target method signature.
Do one of the following:
- Press Alt+Enter and choose Add 'params' modifier and update usages.
- Press Ctrl+Alt+Shift+T and then choose Add 'params' modifier and update usages.
If no conflicts are found, JetBrains Rider performs the refactoring immediately. Otherwise, it prompts you to resolve conflicts.
Right after the refactoring has been completed, all changes that it makes anywhere, including other files, are registered as a single operation. So you can use the Undo action Ctrl+Z to roll back all these changes with a single keystroke.

With this refactoring, you can also perform the reverse transformation by removing the params modifier and updating the usages. This can be helpful ife you need to include new parameters after the last params parameter.

Last modified: 30 July 2024