From cbb7b625a46feeeea250dce7e5b7a3f2755e3e55 Mon Sep 17 00:00:00 2001
From: Rob Muhlestein <rob@rwx.gg>
Date: Sun, 6 Nov 2022 22:31:14 -0500
Subject: [PATCH] Add pre-Call initialization and validation

---
 z/cmd.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/z/cmd.go b/z/cmd.go
index 61e141f..af5efe2 100644
--- a/z/cmd.go
+++ b/z/cmd.go
@@ -59,6 +59,7 @@ type Cmd struct {
 	// where the work happens
 	Caller *Cmd   `json:"-"`
 	Call   Method `json:"-"`
+	Init   Method `json:"-"` // before Commands/Call, good for validation
 
 	// pass bulk input efficiently (when args won't do)
 	Input io.Reader
@@ -298,6 +299,13 @@ func (x *Cmd) Run() {
 		return
 	}
 
+	// initialize before delegation and Call
+	if cmd.Init != nil {
+		if err := cmd.Init(cmd, args...); err != nil {
+			ExitError(err)
+		}
+	}
+
 	// default to first Command if no Call defined
 	if cmd.Call == nil {
 		if len(cmd.Commands) > 0 {
@@ -339,6 +347,7 @@ func (x *Cmd) Run() {
 	if cmd.Caller == nil {
 		cmd.Caller = x
 	}
+
 	if err := cmd.Call(cmd, args...); err != nil {
 		ExitError(err)
 		return