Access context/datasource details as values

[seanorama]

Is it possible to access the details of a context or datasource as values?

For example, I have a file as input:

file://foo/bar/example.yaml

Can that full path or filename be provided as a value that is output by the template?

[hairyhenderson]

This isn't possible currently (except for a specialized case for --output-map). Can you elaborate on why this'd be useful?