Deprecate :: in favor of @ in dotnet new install command

[Forgind]

Per #45156 (comment)

The syntax is currently dotnet new install package::version. It would be good to change it to dotnet new install package@version. We may also want to look to see if there are other instances of :: used as a delimiter where we could change it to @

Thanks @am11 for bringing this up!

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[baronfel]

I approve this - in general we should adopt this syntax for versioned things across the CLI. Next up would be the NuGet commands, which @JonDouglas expressed general approval for in #42367 (comment) as well.

[am11]

Thanks for considering this. I just recalled the conversation we had in an old PR when we were adding dotnet-new-install display template in nuget.org website: NuGet/NuGetGallery#7548. Explicit --version with @ shorthand for all version arguments is an impressive idea! Easy to remember syntax.

[KalleOlaviNiemitalo]

I worried that @ might have to be quoted in PowerShell, because I have seen commands like git log @{u} fail in PowerShell; but apparently PowerShell parses @ as the splatting operator only when it's at the beginning of a word, not when it is part of package@version.

[am11]

Another option is perhaps =. Below are examples of various tools and how they define versions:

• cargo install <name> --version <version> (uses --version)
• apt install <name>=<version> (uses =)
• apk add <name>=<version> (uses =)
• npm install <name>@<version> (uses @)
• pip install <name>==<version> (uses ==)
• choco install <name> --version=<version> (uses --version=)
• winget install <name> --version <version> (uses --version)
• gem install <name> -v <version> (uses -v)
• brew install <name>@<version> (uses @)
• pnpm add <name>@<version> (uses @)
• yay -S <name> --version=<version> (uses --version=)

[Forgind]

I worried that @ might have to be quoted in PowerShell, because I have seen commands like git log @{u} fail in PowerShell; but apparently PowerShell parses @ as the splatting operator only when it's at the beginning of a word, not when it is part of package@version.

I didn't even consider this. Thanks for checking!

[marcpopMSFT]

Triage: add the new command in 10 and add a warning when customers use :: and then in 11 we should remove the old command.