Support build templates

[liufengyun]

Support build templates

What has changed

jo new my-app --template typescope/chord

It is intentional that we keep the template system simple and do not support variables, prompts or hooks.

Checklist

• Added / updated tests under tests/pos/ or tests/warn/
• Docs updated if the change affects user-visible behavior
• All commits are signed off (why?)

How to sign off commits

Use git commit -s to add the Signed-off-by line automatically:

To add a sign-off to the last commit retroactively:

git commit --amend -s --no-edit

To add sign-off to the last 3 commits:

git rebase --signoff HEAD~3

Security impact

No

Compatibility impact

No

• Source compatibility: existing code continue to compile
• SAST compatibility
  • forward compatibility: new libraries can be used by old compiler
  • backward comopatibility: old libraries can be used by new compiler
• Standard Library compatibility:
  • forward compatibility: new code can work with old stdlib
  • backward compatibility: old code work with the new stdlib
• Runtime Library compatibility:
  • forward compatibility: new code can work with old runtime
  • backward compatibility: old code work with the new runtime
• Build tool
  • Build spec compatibility: old projects continue to build
  • Joy package compatibility: old .joy can be consumed by new build tool

[liufengyun]

@necto Could you take a look at this PR when you have time?

[necto]

I don't understand the parenthesis here. which is not preserved? what script to make executable?

[liufengyun]

So, if we copy the template via git, the executable scripts and symlinks are preserved. However, if we download via zip, symlinks and executable bit are lost (ZIP cannot represent them).

[necto]

I'm surprized Scala does not even offer a Json parsing library. no action required

[liufengyun]

Yes, even Java does not have one. It does not matter much, as there are so many 3rd-party libraries.