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Pattern: FluentInterface

Fluent interface allows you do have method chaining.

Purpose of .NET implementation​

The methods of a service collection instance is called multiple times( e.g. for .AddSingleton).
You want to ensure that the programmer can write code that is easy to write, easy to read, and easy to maintain.
So from each method you return the instance of the service collection, so you can chain the methods.

Example in .NET :​

FluentInterface​

FluentInterface example for Pattern FluentInterface

using Microsoft.Extensions.DependencyInjection;
using System.Data;
using System.Data.Common;

namespace FluentInterface;
internal static class FluentInterfaceDemo
{
    public static ServiceCollection AddServices(this ServiceCollection sc)
    {
        //just for demo, does not make sense
        sc
            .AddSingleton<IComparable>((sp) =>
            {
                //does not matter
                return 1970;
            })
            .AddSingleton<IComparable<Int32>>((sp) =>
            {
                //does not matter
                return 16;
            });
        //this way you can chain the calls , making a fluent interface 
        return sc;


    }
}

Download source

See Source Code for Microsoft implementation of FluentInterface​

SourceCode Microsoft.Extensions.DependencyInjection.ServiceCollectionServiceExtensions.AddSingleton

Learn More​

Wikipedia

Homework​

Implement a class person that you can see the first name and last name as fluent interface.