From 0f0f1d4bc8d09cc511e23cccec81d5ac5c77cbbc Mon Sep 17 00:00:00 2001
From: Jakub Sobon <jakub.sobon@elohim.sk>
Date: Thu, 28 Mar 2019 22:50:29 -0400
Subject: [PATCH] Validate the tree only once at creation.

---
 container/container.go | 3 +++
 container/options.go   | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/container/container.go b/container/container.go
index 02cd534..af91c87 100644
--- a/container/container.go
+++ b/container/container.go
@@ -84,6 +84,9 @@ func New(t terminalapi.Terminal, opts ...Option) (*Container, error) {
 	if err := applyOptions(root, opts...); err != nil {
 		return nil, err
 	}
+	if err := validateOptions(root); err != nil {
+		return nil, err
+	}
 	return root, nil
 }
 
diff --git a/container/options.go b/container/options.go
index 9e76583..40b7831 100644
--- a/container/options.go
+++ b/container/options.go
@@ -35,7 +35,11 @@ func applyOptions(c *Container, opts ...Option) error {
 			return err
 		}
 	}
+	return nil
+}
 
+// validateOptions validates options set in the container tree.
+func validateOptions(c *Container) error {
 	// ensure all the container identifiers are either empty or unique.
 	var errStr string
 	seenID := map[string]bool{}