With 6.0.0

.NET Standard 1.6 .NET Framework 4.5
There is a newer prerelease version of this package available.
See the version list below for details.
Install-Package With -Version 6.0.0
dotnet add package With --version 6.0.0
<PackageReference Include="With" Version="6.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add With --version 6.0.0
The NuGet Team does not provide support for this client. Please contact its maintainers for support.
#r "nuget: With, 6.0.0"
#r directive can be used in F# Interactive, C# scripting and .NET Interactive. Copy this into the interactive tool or source code of the script to reference the package.
// Install With as a Cake Addin
#addin nuget:?package=With&version=6.0.0

// Install With as a Cake Tool
#tool nuget:?package=With&version=6.0.0
The NuGet Team does not provide support for this client. Please contact its maintainers for support.

with

With is a small library written in c# intended for alternative constructions in c# to do things that may look clumsy in regular code.

Why is this library small? Parts of the library has been removed as c# has evolved (and my understanding of what can be useful in c#).

What can we learn from "With"

Having access to expressions can help with doing extensions to a language in a relatively simple way.

Examples

Working with immutable data

If you need to get a copy of a readonly object but with some other value set in the new instance, you can use With. This is very similar to f# copy and update record expression. The main abstraction is called a lens. Lenses answers the question "How do you read and update immutable data". It may help to think about them as properties for immutable data that you can combine and compose. For further reading see the Basic lens operation part of the wiki

Simplest example
using With;
using With.Lenses;
...
public class CustomerNameChangeHandler
{
    // start with initializing the lens expression once (main cost is around parsing expressions)
    private static readonly DataLens<Customer, string> NameLens =
        LensBuilder<Customer>
            .Of(m => m.Name)
            .Build();
    public void Handle()
    {
        // fetch customer, say:
        var customer = new Customer(id:1, name:"Johan Testsson");
        // get a new instance of that customer but with changed name:
        var changedNameToErik = CustomerNameLens.Set(customer, "Erik Testsson");
        // ...
    }
}
Settings several properties at the same time
using System;
using With;
using With.Lenses;
...
public class CustomerChangeHandler
{
    // start with initializing the lens expression once (main cost is around parsing expressions)
    private static readonly DataLens<Customer, (int, string, IEnumerable<string>)> CustomerIdNamePreferencesLens =
        LensBuilder<Customer>
            .Of(m => m.Id)
            .And(m => m.Name)
            .And(m => m.Preferences)
            .Build();
    public void Handle()
    {
        // fetch customer, say:
        var customer = new Customer(id:1, name:"Johan Testsson");
        // get a new instance of that customer but with id, name and preferences changed:
        var change = CustomerIdNamePreferencesLens.Set(customer, (NextId(), "Erik Testsson", new []{"Swedish fish"}) );
        // ...
    }
}

Why shouldn't you use this library

The immutable data support in this library is done as an extensions to the language using the expression support in c#. A different way to add these things to c# would be to write some sort of roslyn extension in order to extend the language in a way that can be generated at compile time. This is done for instance in language ext codegen project. An approach such as that could be useful depending on your requirements.

On the .net platform there is already a language that allows you to write immutable first code in a terse and helpful way, f#, you can find out more on: f# for fun and profit. Many programmers prefer to work in c#/java why this library or codegen makes more sense.

Product Versions
.NET net5.0 net5.0-windows net6.0 net6.0-android net6.0-ios net6.0-maccatalyst net6.0-macos net6.0-tvos net6.0-windows
.NET Core netcoreapp1.0 netcoreapp1.1 netcoreapp2.0 netcoreapp2.1 netcoreapp2.2 netcoreapp3.0 netcoreapp3.1
.NET Standard netstandard1.6 netstandard2.0 netstandard2.1
.NET Framework net45 net451 net452 net46 net461 net462 net463 net47 net471 net472 net48
MonoAndroid monoandroid
MonoMac monomac
MonoTouch monotouch
Tizen tizen30 tizen40 tizen60
Xamarin.iOS xamarinios
Xamarin.Mac xamarinmac
Xamarin.TVOS xamarintvos
Xamarin.WatchOS xamarinwatchos
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last updated
6.1.0-beta-1 337 3/12/2020
6.0.0 1,427 12/25/2019
6.0.0-alpha-1 327 12/22/2019
5.1.4 459 12/22/2019
5.1.3 447 12/15/2019
5.1.2 899 11/22/2019
5.1.1 403 11/17/2019
5.1.0 345 11/16/2019
5.1.0-alpha-2 278 11/15/2019
5.1.0-alpha-1 306 11/13/2019
5.0.2 1,073 8/23/2018
5.0.1 669 8/23/2018
5.0.0 675 8/21/2018
4.3.1 1,087 4/11/2018
4.3.0 970 11/8/2017
4.2.0 688 11/2/2017
4.1.2 726 11/1/2017
4.1.1 723 10/3/2017
4.1.0 710 10/3/2017
4.0.0 718 9/18/2017
3.0.0 1,120 9/29/2016
2.0.0 1,028 6/11/2016
1.0.8 1,314 2/1/2016
1.0.7 888 10/12/2015
1.0.6 1,058 9/26/2015
1.0.5 933 9/25/2015
1.0.3 952 9/25/2015
1.0.2 919 9/24/2015
1.0.1 943 9/24/2015
1.0.0 956 9/18/2015
0.4.19 902 9/9/2015
0.4.18 885 8/19/2015
0.4.17 896 6/27/2015
0.4.16 992 3/22/2015
0.4.15 850 3/22/2015
0.4.14 853 3/21/2015
0.4.13 837 3/20/2015
0.4.12 836 3/20/2015
0.4.11 802 3/18/2015
0.4.10 834 3/18/2015
0.4.9 814 3/18/2015
0.4.8 854 3/12/2015
0.4.7 843 3/11/2015
0.4.6 877 3/11/2015
0.4.5 846 3/11/2015
0.4.4 831 3/10/2015
0.4.3 1,117 1/6/2015
0.4.2 1,613 12/19/2014
0.4.1 1,119 12/18/2014
0.4.0 1,120 12/18/2014
0.3.0 1,085 12/8/2014
0.2.0 1,294 11/16/2014
0.1.1 1,635 11/8/2014
0.1.0 1,324 11/6/2014
0.0.6 1,374 11/5/2014
0.0.5 1,141 11/3/2014
0.0.4 1,677 11/2/2014
0.0.3 978 10/20/2013
0.0.2 929 10/18/2013
0.0.1 857 10/17/2013

Trimmed down to what should be essential.