On Fri, Jul 28, 2017, at 09:37 PM, Daniel Holth wrote:

See how trivial it would be to put the delegated sdist generator into the build-backend within the confines of the current PEP?

I agree that delegation within the backend is a reasonable answer to this.

The build-backend could point to a .py in the current directory that implements itself with different tools,

I think this was actually a question that someone (Nathaniel?) brought up: is the project source directory on sys.path when the backend is loaded? I would lean yes, so that it's possible to have a custom backend in the project tree, but I think whoever brought it up before was leaning no.