Re: [ELPA] New package: triples

[Stefan Monnier <monnier@iro.umontreal.ca>]

> About the possibility of using one or the other, whichever is available, how
> would that work in terms of package dependencies? I don't think it's
> possible to have an OR dependency specified in the package-dependencies
> line in the source, but really only one of emacsql or emacs29 would be
> required.  If you have any insight into this, it'd be useful.

Package dependencies just tell the package manager to install other
packages to try and make it easier on users to get a working package.
But you don't need to have a precise/exact description of the
real dependencies in the `Package-Requires` (as long as the
correct byte-compilation of your package actually depends on some other
package, e.g. if your package uses a macro defined in the other package).

You can just remove the `emacsql` dependency from `Package-Requires` and
replace it with a runtime check for the presence of either `emacsql` or
the new sqlite support that emits an error when applicable (with
a message explaining to the user that they need to have one of those two
thingies before they can use the package).
[ Just make sure the error is not emitted just because the file(s) from
  your package are loaded, but only when some code is actually called.  ]


        Stefan