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Is there any way to use System.CommandLine with .NET Framework 4.5 (which I need to use due to reasons I can't influence)?

I have used it with later .NET Framework versions without any issues, but unfortunately need to switch back to .NET Framework 4.5

  • Getting it via NuGet obviously does not work due to compatibility
  • Setting the project to a higher version, getting it via NuGet, setting the project back to .NET Framework 4.5 leaves me with an error, that the static async Task<int> Main(string[] args) is not what is expected and the Program does not contain a static 'Main' method suitable for an entry point

Any workaround to this? Thank you!

nogenius
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  • .NET 4.5 has been unsupported for quite a while and few systems actually run vanilla 4.5. Most have been updated to a more recent (but still compatible) version of .NET 4.x, or can easily do so. `System.CommandLine` targets .NET Standard 2.0 and is therefore compatible with .NET 4.6.1 and up -- you should be able to target your project to that without losing much if any deployment compatibility. – Jeroen Mostert Dec 06 '22 at 15:05
  • Note that 4.6.1 itself has also been unsupported for quite a while, but this doesn't matter for targeting purposes. If you can, of course, upgrade to the latest possible version of .NET Framework on the deployment machine, regardless of what you're targeting (as of writing, that's 4.8.1). – Jeroen Mostert Dec 06 '22 at 15:12

1 Answers1

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Is there any way to use System.CommandLine with .NET Framework 4.5 (which I need to use due to reasons I can't influence)?

Short answer: No, not without considerable effort.

Long answer: The source code of System.CommandLine is available publicly under the MIT license, which means (among other things) that you are allowed to modify the code to suit your needs. This includes backporting it to an earlier version of the .NET Framework. Thus, you could

  • download the source code,
  • change its target framework to 4.5,
  • fix all the errors, and then
  • compile and use it in your project.

If you really need this, you'll probably have to do all the work yourself: Since .NET Framework 4.5 is out of support, it's quite unlikely that anyone else needs this and/or is motivated to work on this.

Regarding the concrete problem you mentioned in your question: Here's how to work around the lack of async Main in earlier versions of C#:

Heinzi
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