From 1e6f15faac463b6a5e2f1ff63aaab9677b92cdfc Mon Sep 17 00:00:00 2001
From: Artem Klevtsov <a.a.klevtsov@gmail.com>
Date: Sun, 17 Sep 2023 06:39:43 +0700
Subject: [PATCH] Add EnvFlag util (#378)

---
 README.md | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 35b07c6..d465dba 100644
--- a/README.md
+++ b/README.md
@@ -337,6 +337,40 @@ func main() {
 }
 ```
 
+Another example of using hooks is load the env-file:
+
+```go
+package main
+
+import (
+  "fmt"
+  "github.com/alecthomas/kong"
+  "github.com/joho/godotenv"
+)
+
+type EnvFlag string
+
+// BeforeResolve loads env file.
+func (c EnvFlag) BeforeReset(ctx *kong.Context, trace *kong.Path) error {
+  path := string(ctx.FlagValue(trace.Flag).(EnvFlag)) // nolint
+  path = kong.ExpandPath(path)
+  if err := godotenv.Load(path); err != nil {
+    return err
+  }
+  return nil
+}
+
+var CLI struct {
+  EnvFile EnvFlag
+  Flag `env:"FLAG"`
+}
+
+func main() {
+  _ = kong.Parse(&CLI)
+  fmt.Println(CLI.Flag)
+}
+```
+
 ## Flags
 
 Any [mapped](#mapper---customising-how-the-command-line-is-mapped-to-go-values) field in the command structure *not* tagged with `cmd` or `arg` will be a flag. Flags are optional by default.
@@ -704,4 +738,4 @@ See the [section on hooks](#hooks-beforeresolve-beforeapply-afterapply-and-the-b
 
 ### Other options
 
-The full set of options can be found [here](https://godoc.org/github.com/alecthomas/kong#Option).
\ No newline at end of file
+The full set of options can be found [here](https://godoc.org/github.com/alecthomas/kong#Option).