On Friday, 24 February 2023 at 19:37:41 UTC, Steven Schveighoffer
wrote:
On 2/24/23 2:01 PM, jmh530 wrote:
I'm looking at the dub package format [1] about optional
dependencies and it says:
"With this set to true, the dependency will only be used if
explicitly selected in dub.selections.json. If omitted, this
attribute defaults to false."
And it occurs to me that I don't know anything about how
dub.selections.json works.
Let's say you have dependency A, which has an *optional*
dependency on B.
In your project, if you depend on A, but don't explicitly
depend on B, then A will be built without B as a dependency.
If you have a dependency on A *and* B, then B's optional
dependency will kick in, and participate in the selection of
it's version.
So for instance, you could depend on B version 1 or higher, and
the optional dependency could be on v1.5 or higher, it will
select the highest version of 1.5
dub.selections.json only applies to the primary project. So the
decision on which versions of which dependencies to use is
decided by the whole tree.
-Steve
Ok this makes sense. So it's all about dependencies downstream.
For instance, if I list B as a dependency in my project but never
use it in my own project, it will still compile in (so for
instance if A's functionality differs depending on if B is
included, then I will get that functionality even if I don't use
B directly in my project).
