Fluentify 1.0.0

There is a newer version of this package available.
See the version list below for details.
dotnet add package Fluentify --version 1.0.0                
NuGet\Install-Package Fluentify -Version 1.0.0                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Fluentify" Version="1.0.0">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
</PackageReference>                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Fluentify --version 1.0.0                
#r "nuget: Fluentify, 1.0.0"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install Fluentify as a Cake Addin
#addin nuget:?package=Fluentify&version=1.0.0

// Install Fluentify as a Cake Tool
#tool nuget:?package=Fluentify&version=1.0.0                

Fluentify NuGet GitHub

Fluentify is a .NET Roslyn Source Generator designed to automate the creation of Fluent APIs. This tool enables engineers to rapidly develop rich, expressive, and maintainable APIs with ease. Utilizing Fluentify allows for cleaner code, easier maintenance, and more expressive interactions within your C# .NET applications.

Installation

To install Fluentify, use the following command in your package manager console:

install-package Fluentify

Usage

Fluentify automatically creates extension methods for each property on types that have the Fluentify attribute, supporting both class and record types.

Class Type Usage

Class types are supported as long as the type has an accessible default constructor.

[Fluentify]
public class Person
{
    public ushort Age { get; init; }
    public string[] Aliases { get; init; }
    public DateOnly DateOfBirth { get; init; }
    public Name Name { get; init; }
}

Record Type Usage

Record types are supported without the need for any special provisions

[Fluentify]
public record Person(ushort Age, string[] Aliases, DateOnly DateOfBirth, Name Name);

Marking the record type as partial will generate a default constructor, allowing for the record to be instantiated without first initializing the properties.

[Fluentify]
public partial record Person(ushort Age, string[] Aliases, DateOnly DateOfBirth, Name Name);

// Allows for instantiation without property initialization
var person = new Person();
...

Immutability

The generated extension methods preserve immutability, providing a new instance with the specified value applied to the associated property.

var original = new Person { Age = 42 };
var @new = original.WithAge(75);

Console.WriteLine(original.Age); // Displays 42
Console.WriteLine(@new.Age);     // Displays 75

Auto Instantiation

The value associated with a given property can be automatically instantiated, as long as that type associated with the property adheres to the new() constraint. A second extension method is generated for the property, accepting a Func<T, T> delegate as its parameter, which allows for the newly instantiated value to be configured before being applied.

_ = person.WithName(name => name
    .WithGiven("Avery")
    .WithFamily("Brooks"));

Collection Parameterization

Values can be appended to a list as long as the property type is T[], IEnumerable<T>, IReadOnlyCollection<T>, IReadOnlyList<T>. Property types that derive from ICollection<T> and adhere to the new() constraint are also supported. Unlike with scalar properties, the generated extension method accepts a params T[], allowing for one or more values to be specified in a single invocation.

var original = new Person { Aliases = ["Avery Franklin"] };
var @new = original.WithAliases("Benjamin Sisko");

Console.WriteLine(original.Aliases.Length); // Displays 1
Console.WriteLine(@new.Aliases.Length);     // Displays 2

Custom Descriptors

The name of the generated extension method(s) can be customized via the Descriptor attribute.

Class Type Usage

[Fluentify]
public class Person
{
    [Descriptor("Aged")]
    public ushort Age { get; init; }

    [Descriptor("BornOn")]
    public DateOnly DateOfBirth { get; init; }

    [Descriptor("Named")]
    public Name Name { get; init; }
}

Record Type Usage

[Fluentify]
public record Person(
  [Descriptor("Aged")] ushort Age,
  [Descriptor("BornOn")] DateOnly DateOfBirth,
  [Descriptor("Named")] Name Name);

This allows for greater alignment with domain semantics:

_ = person
    .Aged(75)
    .Named(name => name
        .WithGiven("Avery")
        .WithFamily("Brooks"))
    .BornOn(new DateOnly(1948, 10, 2));

When no custom descriptor is specified, the extension method(s) will use the following pattern for all property types, except bool:

With{PropertyName}

For bool, the extension method will utilize the same name as the property.

Property Exclusion

Specific properties can be excluded from generating Fluentify extension method(s) using the Ignore attribute:

Class Type Usage

[Fluentify]
public sealed class Person
{
    [Ignore]
    public ushort Age { get; init; }
    public DateOnly DateOfBirth { get; init; }
    public Name Name { get; init; }
}

Record Type Usage

[Fluentify]
public record Person([Ignore] ushort Age, DateOnly DateOfBirth, Name Name);

This will result in an error if you try to use the ignored property in the chain:

_ = person
    .WithAge(75) // IntelliSense Error: 'Person' does not contain a definition for 'WithAge'
    .WithName(name => name
        .WithGiven("Avery")
        .WithFamily("Brooks"))
    .WithDateOfBirth(new DateOnly(1948, 10, 2));

Analyzers

Fluentify includes several analyzers to assist engineers with its usage. These are:

Rule ID Category Severity Notes
FLTFY01 Design Warning Class must have an accessible parameterless constructor to use Fluentify
FLTFY02 Usage Info Descriptor is disregarded from consideration by Fluentify
FLTFY03 Usage Info Type does not utilize Fluentify
FLTFY04 Naming Warning Descriptor must adhere to the naming conventions for Methods
FLTFY05 Usage Info Type does not utilize Fluentify
FLTFY06 Usage Info Property is already disregarded from consideration by Fluentify

How to Apply in Practice

If you are unfamiliar with Fluent Builder pattern, please review Building Complex Objects in a Simple Way with C# by Gui Ferreira.

If we take the example of the MovieBuilder and apply Fluentify, it may look like this:

[Fluentify]
public partial record Actor(
    [Descriptor("BornIn")] int Birthday,
    string FirstName,
    string Surname);

[Fluentify]
public partial record Movie(
    Actor[] Actors,
    [Descriptor("OfGenre")] Genre Genre,
    [Descriptor("ReleasedOn")] DateOnly ReleasedOn,
    string Title);

In this example, we did not need to create the various With methods, nor did we need to explicitly create the Build method, significantly reducing the effort required by the engineer to support the highly expressive Fluent approach to building the Movie instance, demonstrated as follows:

var actual = new Movie()
   .OfGenre(Genre.SciFi)
   .WithTitle("Star Trek: First Contact")
   .ReleasedOn(new DateOnly(1996, 12, 13))
   .WithActors(actor => actor
       .WithFirstName("Patrick")
       .WithSurname("Stewart")
       .BornIn(1940));

Naturally, using Fluentify does not preclude engineers from adding additional methods to support building, and this will often be required if you choose to adopt the guided builder approach, or if specific validations or conversions are required before the final instance can be built. For example:

public class MyService
{
    public MyService(string connectionString, TimeSpan timeout)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(connectionString);
        ArgumentOutOfRangeException.ThrowIfLessThan(timeout.TotalSeconds, 1);

        ConnectionString = connectionString;
        Timeout = timeout;
    }

    public string ConnectionString { get; }

    public TimeSpan Timeout { get; }
}

[Fluentify]
public partial record MyServiceBuilder(
    [Descriptor("ConnectsTo")]string ConnectionString,
    [Descriptor("Waits")] int Timeout)
{
    public static MyServiceBuilder Empty => new();
    
    public MyService Build()
    {
        return new MyService(ConnectionString, TimeSpan.FromSeconds(Timeout));
    }
}

In this example, a new instance of MyService can be created as follows:

MyService service = MyServiceBuilder
    .Empty
    .ConnectsTo("Some Connection String")
    .Waits(30)
    .Build();

Contributing

Contributions are welcome! Please feel free to submit pull requests or open issues to suggest improvements or add new features.

License

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

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
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