From 4d2332582355c0b4c70d7817e569139d502d97a1 Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Tue, 17 May 2022 11:56:17 -0600
Subject: [PATCH] Implement cfg.BoolVar method

---
 srv/src/cfg/cfg.go      | 21 +++++++++++++++++++++
 srv/src/cfg/cfg_test.go | 21 +++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/srv/src/cfg/cfg.go b/srv/src/cfg/cfg.go
index 32fc3e7..d87c45b 100644
--- a/srv/src/cfg/cfg.go
+++ b/srv/src/cfg/cfg.go
@@ -211,6 +211,27 @@ func (c *Cfg) Int(name string, value int, usage string) *int {
 	return p
 }
 
+// BoolVar is equivalent to flag.FlagSet's BoolVar method, but will additionally
+// set up an environment variable for the parameter.
+func (c *Cfg) BoolVar(p *bool, name string, value bool, usage string) {
+
+	envName := c.envifyName(name)
+
+	c.flagSet.BoolVar(p, name, value, envifyUsage(envName, usage))
+
+	if valStr := c.params.Env[envName]; valStr != "" {
+		*p = valStr != "" && valStr != "0" && valStr != "false"
+	}
+}
+
+// Bool is equivalent to flag.FlagSet's Bool method, but will additionally set
+// up an environment variable for the parameter.
+func (c *Cfg) Bool(name string, value bool, usage string) *bool {
+	p := new(bool)
+	c.BoolVar(p, name, value, usage)
+	return p
+}
+
 // SubCmd should be called _after_ Init. Init will have consumed all arguments
 // up until the first non-flag argument. This non-flag argument is a
 // sub-command, and is returned by this method. This method also resets Cfg's
diff --git a/srv/src/cfg/cfg_test.go b/srv/src/cfg/cfg_test.go
index 7ccf94a..8266c89 100644
--- a/srv/src/cfg/cfg_test.go
+++ b/srv/src/cfg/cfg_test.go
@@ -44,3 +44,24 @@ func TestIntVar(t *testing.T) {
 	assert.Equal(t, 222, bar)
 	assert.Equal(t, 333, baz)
 }
+
+func TestBoolVar(t *testing.T) {
+
+	cfg := New(Params{
+		Args: []string{"--foo=1"},
+		Env:  map[string]string{"FOO": "0", "BAR": "anything", "BIZ": "0"},
+	})
+
+	var foo, bar, baz, biz bool
+
+	cfg.BoolVar(&foo, "foo", false, "")
+	cfg.BoolVar(&bar, "bar", false, "")
+	cfg.BoolVar(&baz, "baz", false, "")
+	cfg.BoolVar(&biz, "biz", true, "")
+
+	assert.NoError(t, cfg.Init(context.Background()))
+	assert.Equal(t, true, foo)
+	assert.Equal(t, true, bar)
+	assert.Equal(t, false, baz)
+	assert.Equal(t, false, biz)
+}