From d15c8fca8dfd0f4dba023021118452517cf36d9a Mon Sep 17 00:00:00 2001
From: Alec Thomas <alec@swapoff.org>
Date: Wed, 30 Oct 2019 13:46:08 +1100
Subject: [PATCH] Bind parent nodes when executing Run().

---
 callbacks.go | 11 ++++++++++-
 context.go   | 16 +++++++++++-----
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/callbacks.go b/callbacks.go
index 7f4637b..e403d27 100644
--- a/callbacks.go
+++ b/callbacks.go
@@ -3,10 +3,19 @@ package kong
 import (
 	"fmt"
 	"reflect"
+	"strings"
 )
 
 type bindings map[reflect.Type]reflect.Value
 
+func (b bindings) String() string {
+	out := []string{}
+	for k := range b {
+		out = append(out, k.String())
+	}
+	return "bindings{" + strings.Join(out, ", ") + "}"
+}
+
 func (b bindings) add(values ...interface{}) bindings {
 	for _, v := range values {
 		b[reflect.TypeOf(v)] = reflect.ValueOf(v)
@@ -51,7 +60,7 @@ func callMethod(name string, v, f reflect.Value, bindings bindings) error {
 		if arg, ok := bindings[pt]; ok {
 			in = append(in, arg)
 		} else {
-			return fmt.Errorf("couldn't find binding of type %s for parameter %d of %T.%s(), use kong.Bind(%s)", pt, i, v.Type(), name, pt)
+			return fmt.Errorf("couldn't find binding of type %s for parameter %d of %s.%s(), use kong.Bind(%s)", pt, i, v.Type(), name, pt)
 		}
 	}
 	out := f.Call(in)
diff --git a/context.go b/context.go
index 7279f63..80c262f 100644
--- a/context.go
+++ b/context.go
@@ -525,8 +525,9 @@ func (c *Context) parseFlag(flags []*Flag, match string) (err error) {
 
 // Run executes the Run() method on the selected command, which must exist.
 //
-// Any passed values will be bindable to arguments of the target Run() method.
-func (c *Context) Run(bindings ...interface{}) (err error) {
+// Any passed values will be bindable to arguments of the target Run() method. Additionally,
+// all parent nodes in the command structure will be bound.
+func (c *Context) Run(binds ...interface{}) (err error) {
 	defer catch(&err)
 	node := c.Selected()
 	if node == nil {
@@ -535,12 +536,18 @@ func (c *Context) Run(bindings ...interface{}) (err error) {
 	type targetMethod struct {
 		node   *Node
 		method reflect.Value
+		binds  bindings
 	}
+	methodBinds := c.Kong.bindings.clone().add(binds...).add(c).merge(c.bindings)
 	methods := []targetMethod{}
 	for i := 0; node != nil; i, node = i+1, node.Parent {
 		method := getMethod(node.Target, "Run")
+		methodBinds = methodBinds.clone()
+		for p := node; p != nil; p = p.Parent {
+			methodBinds = methodBinds.add(p.Target.Addr().Interface())
+		}
 		if method.IsValid() {
-			methods = append(methods, targetMethod{node, method})
+			methods = append(methods, targetMethod{node, method, methodBinds})
 		}
 	}
 	if len(methods) == 0 {
@@ -552,8 +559,7 @@ func (c *Context) Run(bindings ...interface{}) (err error) {
 	}
 
 	for _, method := range methods {
-		binds := c.Kong.bindings.clone().add(bindings...).add(c).merge(c.bindings)
-		if err = callMethod("Run", method.node.Target, method.method, binds); err != nil {
+		if err = callMethod("Run", method.node.Target, method.method, method.binds); err != nil {
 			return err
 		}
 	}