Create a .NET Standard Library with Visual Studio 2017

It has been almost a year since I wrote this post on creating a .NET Standard Library which was before Visual Studio 2017 was released. This post is going to cover the same basic idea, but for the new tooling which has vastly simplified the process.

.NET Standard Library

The .NET Standard Library specifies what .NET APIs are available based on the version of the .NET Standard Library being implemented. The following is a comparison to portable class libraries that really helped me understand the difference. This was pulled from the .NET Standard Library link above.

.NET Standard Library can be thought of as the next generation of Portable Class Libraries (PCL). The .NET Standard Library improves on the experience of creating portable libraries by curating a standard BCL and establishing greater uniformity across .NET runtimes as a result. A library that targets the .NET Standard Library is a PCL or a “.NET Standard-based PCL”. Existing PCLs are “profile-based PCLs”.

The .NET Standard Library and PCL profiles were created for similar purposes but also differ in key ways.

Similarities:

  • Defines APIs that can be used for binary code sharing.

Differences:

  • The .NET Standard Library is a curated set of APIs, while PCL profiles are defined by intersections of existing platforms.
  • The .NET Standard Library linearly versions, while PCL profiles do not.
  • PCL profiles represents Microsoft platforms while the .NET Standard Library is agnostic to platform.

Create a .NET Standard Library

In Visual Studio click File > New > Project.

This will launch the New Project dialog. Find the .NET Standard templates and select Class Library.

Now that the library has been created right click on the project and go to properties. On the Application tab, there is an option to for Target framework which currently defaults to .NETStandard 1.4. Depending on your platform your library needs to support will decide which version of the .NET Standard you need to use.

See the chart on this page for help with picking a version of the standard. The lower the version of the standard you target the more platforms your library will run on, but keep in mind the lower the version the smaller the API surface that is available.

Wrapping up

This process is so much easier than it was in Visual Studio 2015. The tooling around .NET Core and .NET Standard has gotten so much better. This type of library is the future and I highly recommend using .NET Standard when you have the option over portable class libraries.


Also published on Medium.

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