From 756ae621bd97a8b776fefb15e5e7e2292f98ee45 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Thu, 9 Jul 2026 00:14:33 +0300
Subject: dependencies

---
 api/options/option.go | 21 +++++++++++++++++++++
 api/resource.go       |  4 ++++
 2 files changed, 25 insertions(+)

(limited to 'api')

diff --git a/api/options/option.go b/api/options/option.go
index 1d9b931..22156a8 100644
--- a/api/options/option.go
+++ b/api/options/option.go
@@ -5,6 +5,8 @@ package options
 import (
 	"log"
 	"os"
+
+	"codeberg.org/snonux/gonf/internal/resource"
 )
 
 // Option configures a resource. It is applied to the concrete resource value
@@ -22,12 +24,31 @@ type (
 	Prunable   interface{ SetPrune() }
 	Absentable interface{ SetAbsent() }
 	Latestable interface{ SetLatest() }
+	Dependable interface{ AddDependency(id string) }
 	Linkable   interface {
 		SetSymlink(target string)
 		SetHardlink(target string)
 	}
 )
 
+// DependsOn declares that the resource being configured must be applied only
+// after every given resource has been applied. Each argument may be a single
+// resource or a Multi; a Multi is expanded so the dependency is recorded for
+// each of its members individually.
+func DependsOn(deps ...resource.Dependency) Option {
+	return func(t any) {
+		r, ok := t.(Dependable)
+		if !ok {
+			log.Fatalf("%T does not support DependsOn", t)
+		}
+		for _, dep := range deps {
+			for _, id := range dep.Dependencies() {
+				r.AddDependency(id)
+			}
+		}
+	}
+}
+
 // WithOwner sets the owning user of the resource.
 func WithOwner(owner string) Option {
 	return func(t any) {
diff --git a/api/resource.go b/api/resource.go
index e254e1b..5c95211 100644
--- a/api/resource.go
+++ b/api/resource.go
@@ -10,6 +10,10 @@ import (
 type Resource interface {
 	ID() string
 	String() string
+	// Dependencies returns the flattened resource IDs this value represents,
+	// so it can be passed to the DependsOn option. A single resource yields
+	// its own ID; a Multi yields the IDs of all its members.
+	Dependencies() []string
 }
 
 func Apply() error {
-- 
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