OK, I implemented this API in 2.018.7. If it suits you, I'll update the documentation. Otherwise, please tell me what you would like it to look like.
Is this compatible with an ASDF user who is using the old-school ASDF:*CENTRAL-REGISTRY* way of configuring ASDF instead of the new DSL?
If not, is there some way for someone using this API to infer whether the current use is along the lines of ASDF:*CENTRAL-REGISTRY* or the DSL?
There is no plan to stop supporting the "old-school" asdf:*central-registry*. When used, it always takes precedence over the "new-fangled" source-registry.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org A man is usually more careful of his money than he is of his principles. — Edgar Watson Howe