NotifyGen 1.0.0

NotifyGen

A C# source generator that eliminates INotifyPropertyChanged boilerplate.

NotifyGen automatically generates property implementations with change notification from annotated fields. No runtime reflection, no IL weaving, just clean generated code.

Features

• Zero boilerplate - Just add [Notify] to your class
• Compile-time generation - No runtime overhead
• Equality guards - Only raises PropertyChanged when values actually change
• Partial hooks - OnXxxChanged() methods for custom logic
• Dependent properties - [NotifyAlso] for computed properties
• IDE support - Full IntelliSense for generated properties
• Nullable aware - Handles nullable reference types correctly

Installation

dotnet add package NotifyGen

Or via NuGet Package Manager:

Install-Package NotifyGen

Quick Start

using NotifyGen;

[Notify]
public partial class Person
{
    private string _name;
    private int _age;
    private string? _email;
}

That's it! NotifyGen generates the following:

public partial class Person : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler? PropertyChanged;

    public string Name
    {
        get => _name;
        set
        {
            if (EqualityComparer<string>.Default.Equals(_name, value)) return;
            _name = value;
            OnPropertyChanged();
            OnNameChanged();
        }
    }

    public int Age
    {
        get => _age;
        set
        {
            if (EqualityComparer<int>.Default.Equals(_age, value)) return;
            _age = value;
            OnPropertyChanged();
            OnAgeChanged();
        }
    }

    public string? Email
    {
        get => _email;
        set
        {
            if (EqualityComparer<string?>.Default.Equals(_email, value)) return;
            _email = value;
            OnPropertyChanged();
            OnEmailChanged();
        }
    }

    protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    partial void OnNameChanged();
    partial void OnAgeChanged();
    partial void OnEmailChanged();
}

Attributes

[Notify]

Apply to a partial class to enable property generation for all private fields with underscore prefix.

[Notify]
public partial class ViewModel
{
    private string _title;     // Generates Title property
    private int _count;        // Generates Count property
}

Requirements:

• Class must be partial
• Fields must be private
• Fields must start with underscore (_fieldName → FieldName)

[NotifyIgnore]

Exclude a field from property generation.

[Notify]
public partial class ViewModel
{
    private string _name;           // Generates Name property

    [NotifyIgnore]
    private string _internalCache;  // No property generated
}

[NotifyAlso]

Notify additional properties when this field changes. Useful for computed/dependent properties.

[Notify]
public partial class Person
{
    [NotifyAlso("FullName")]
    private string _firstName;

    [NotifyAlso("FullName")]
    private string _lastName;

    public string FullName => $"{FirstName} {LastName}";
}

When FirstName or LastName changes, PropertyChanged is also raised for FullName.

You can notify multiple properties:

[NotifyAlso("FullName")]
[NotifyAlso("DisplayName")]
private string _firstName;

Partial Hooks

Every generated property includes a partial method hook that's called after the value changes:

[Notify]
public partial class Settings
{
    private bool _darkMode;

    partial void OnDarkModeChanged()
    {
        // Called whenever DarkMode changes
        ApplyTheme(DarkMode ? Theme.Dark : Theme.Light);
    }
}

Analyzer Diagnostics

NotifyGen includes analyzers to catch common mistakes:

Requirements

• .NET Standard 2.0+ (works with .NET Framework 4.6.1+, .NET Core, .NET 5+)
• C# 9.0+ (for source generators)

Comparison to Alternatives

Troubleshooting

Properties not generating?

1. Ensure your class is partial
2. Ensure fields are private
3. Ensure fields start with underscore (_name, not name)
4. Rebuild the solution

IntelliSense not showing generated properties?

1. Rebuild the solution
2. Restart your IDE
3. Check that the NotifyGen package is properly referenced

Build errors after adding [Notify]?

Check the Error List for NOTIFY001/NOTIFY002 diagnostics - they provide guidance on what's wrong.

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.

License

This project is licensed under the MIT License - see the LICENSE file for details.