C# Create Derived Class

Adds a Code Action for C# files that generates a derived class based on the selected base class.
The generated class includes constructors, abstract member overrides, generic handling, and cursor positioning for faster editing.

✨ Features

🔹 Create derived class

When the cursor is on a class declaration, a Code Action appears:

Create derived class MyBaseDerived

The extension will:

• detect the class name automatically
• suggest <BaseClassName>Derived as the default derived name
• detect namespace
• create a .cs file in the same folder
• open the file and position cursor at the main implementation point

🔹 Generic class support

Works with:

class MyBase<T>

Generated:

class MyBaseDerived : MyBase<T>

Multi-cursor is automatically placed on generic parameters for batch editing.

🔹 Constructor generation

If the base class has constructors with parameters, corresponding constructors are generated:

Base:

public MyBase(int x, string name) { }

Generated:

public MyBaseDerived(int x, string name) : base(x, name)
{
}

Supports:

• reference modifiers (ref, in, out)
• default parameter values
• constructors with different accessibility (public, protected, etc.)

🔹 Abstract method generation

Base:

public abstract Task ProcessAsync(int id);
protected abstract TResult Transform<T>(T data) where T : class;

Generated:

public override Task ProcessAsync(int id)
{
    throw new System.NotImplementedException();
}

protected override TResult Transform<T>(T data) where T : class
{
    throw new System.NotImplementedException();
}

Supports:

• generic methods
• constraints where T : ...
• return types including generic return types

🔹 Abstract property generation

Base:

public abstract T Data { get; set; }
public abstract string Name { get; }
public abstract int Count { get; init; }

Generated:

public override T Data { get; set; }

public override string Name { get; }

public override int Count { init; }

▶ How to Use

1. Open any .cs file
2. Move the cursor to a line like:

public class MyBase

3. Press:

• Ctrl+.
• Alt+Enter
• or click the 💡 lightbulb

4. Choose:

Create derived class 'MyBaseDerived'

5. Enter name if necessary
6. The extension will create and open a new file

🔧 Build and Debug

npm install
npm run compile

Press F5 to launch extension development host.

🧪 Installation from VSIX

After packaging:

vsce package

Then:

code --install-extension *.vsix

📄 License

MIT

📌 Changelog

0.0.5 — Minor fixes

0.0.4 — Added abstract property generation

• Added support for generating overrides for abstract properties
• Handles get, set, and init accessors
• All NotImplemented blocks use expression bodies

0.0.3 — Added abstract method generation

• Generates overrides for abstract methods
• Supports generic abstract methods
• Supports where constraints

0.0.2 — Constructor generation

• Detects base constructors with arguments
• Generates matching constructors with base(...) call
• Preserves modifiers ref/out/in, and default values

0.0.1 — Initial release

• Generates derived class from base class
• Detects namespace automatically
• Multi-cursor positioning on generic parameters
• Suggestion for default derived class name
• Cursor positioned at implementation location