back: add qver package to track qid versions

1 files changed, 32 insertions, 0 deletions

diff --git a/back/qver/options.go b/back/qver/options.go
new file mode 100644
index 0000000..41385ce
--- /dev/null
+++ b/back/qver/options.go
@@ -0,0 +1,32 @@
+package qver
+
+type Option func(*options)
+
+type options struct {
+	parent *Version
+	UpdateFunc
+	state interface{}
+}
+
+func parse(opts ...Option) options {
+	var o options
+	for _, opt := range opts {
+		opt(&o)
+	}
+	return o
+}
+
+// Whenever the version changes, bump the parent's version as well.
+func Parent(p *Version) Option {
+	return func(o *options) {
+		o.parent = p
+	}
+}
+
+// Call f(state) to update the version whenever Version.Get() is called.
+func Update(state interface{}, f UpdateFunc) Option {
+	return func(o *options) {
+		o.UpdateFunc = f
+		o.state = state
+	}
+}