Re: [PROPOSAL] Builder, a build system integration for Emacs

[Yuri Khan]

On Mon, 29 May 2023 at 04:48, Richard Stallman <rms@gnu.org> wrote:

> What sort of "constraints on versions of their dependencies" are possible?
> Are these numeric comparisons?

A version number is typically a triple of integers, written as
major.minor.patch. A total ordering is defined on version numbers,
using lexicographic order on these three components: 2.0.0 < 2.0.1 <
2.0.10 < 2.1.15 < 3.0.0.

There is a widely used convention (called *semantic versioning*
<https://semver.org/>) that a library author increments the patch
version when the changes are both forward and backward compatible;
minor version when the changes are only backward compatible (a program
depending on the older API builds and runs successfully with a newer
implementation); and major version when introducing breaking changes.

With that convention, the most useful type of version constraint is a
half-open interval expressing “I want version x.y.0 or higher, but
strictly lower than z.0.0”.