Add FlagSet parameter 'ShowZeroValue' to show zero value in usage mes…

…sage
spf13 · Feb 7, 2018 · 71c89ff · 71c89ff
1 parent 4c012f6
commit 71c89ff
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Showing 2 changed files with 71 additions and 1 deletion.
diff --git a/flag.go b/flag.go
@@ -138,6 +138,10 @@ type FlagSet struct {
 	// help/usage messages.
 	SortFlags bool
 
+	// ShowZeroValue is used to indicate, if user wants to show zero value in
+	// help/usage messages.
+	ShowZeroValue bool
+
 	name              string
 	parsed            bool
 	actual            map[NormalizedName]*Flag
@@ -693,7 +697,7 @@ func (f *FlagSet) FlagUsagesWrapped(cols int) string {
 		}
 
 		line += usage
-		if !flag.defaultIsZeroValue() {
+		if f.ShowZeroValue || !flag.defaultIsZeroValue() {
 			if flag.Value.Type() == "string" {
 				line += fmt.Sprintf(" (default %q)", flag.DefValue)
 			} else {

diff --git a/flag_test.go b/flag_test.go
@@ -1117,6 +1117,72 @@ func TestPrintDefaults(t *testing.T) {
 	}
 }
 
+const defaultOutputWithZeroValue = `      --A                         for bootstrapping, allow 'any' type (default false)
+      --Alongflagname             disable bounds checking (default false)
+  -C, --CCC                       a boolean defaulting to true (default true)
+      --D path                    set relative path for local imports (default "")
+  -E, --EEE num[=1234]            a num with NoOptDefVal (default 4321)
+      --F number                  a non-zero number (default 2.7)
+      --G float                   a float that defaults to zero (default 0)
+      --IP ip                     IP address with no default (default <nil>)
+      --IPMask ipMask             Netmask address with no default (default <nil>)
+      --IPNet ipNet               IP network with no default (default <nil>)
+      --Ints ints                 int slice with zero default (default [])
+      --N int                     a non-zero int (default 27)
+      --ND1 string[="bar"]        a string with NoOptDefVal (default "foo")
+      --ND2 num[=4321]            a num with NoOptDefVal (default 1234)
+      --StringArray stringArray   string array with zero default (default [])
+      --StringSlice strings       string slice with zero default (default [])
+      --Z int                     an int that defaults to zero (default 0)
+      --custom custom             custom Value implementation (default 0)
+      --customP custom            a VarP with default (default 10)
+      --maxT timeout              set timeout for dial (default 0s)
+  -v, --verbose count             verbosity (default 0)
+`
+
+func TestPrintDefaultsWithZeroValue(t *testing.T) {
+	fs := NewFlagSet("print defaults test", ContinueOnError)
+	fs.ShowZeroValue = true
+	var buf bytes.Buffer
+	fs.SetOutput(&buf)
+	fs.Bool("A", false, "for bootstrapping, allow 'any' type")
+	fs.Bool("Alongflagname", false, "disable bounds checking")
+	fs.BoolP("CCC", "C", true, "a boolean defaulting to true")
+	fs.String("D", "", "set relative `path` for local imports")
+	fs.Float64("F", 2.7, "a non-zero `number`")
+	fs.Float64("G", 0, "a float that defaults to zero")
+	fs.Int("N", 27, "a non-zero int")
+	fs.IntSlice("Ints", []int{}, "int slice with zero default")
+	fs.IP("IP", nil, "IP address with no default")
+	fs.IPMask("IPMask", nil, "Netmask address with no default")
+	fs.IPNet("IPNet", net.IPNet{}, "IP network with no default")
+	fs.Int("Z", 0, "an int that defaults to zero")
+	fs.Duration("maxT", 0, "set `timeout` for dial")
+	fs.String("ND1", "foo", "a string with NoOptDefVal")
+	fs.Lookup("ND1").NoOptDefVal = "bar"
+	fs.Int("ND2", 1234, "a `num` with NoOptDefVal")
+	fs.Lookup("ND2").NoOptDefVal = "4321"
+	fs.IntP("EEE", "E", 4321, "a `num` with NoOptDefVal")
+	fs.ShorthandLookup("E").NoOptDefVal = "1234"
+	fs.StringSlice("StringSlice", []string{}, "string slice with zero default")
+	fs.StringArray("StringArray", []string{}, "string array with zero default")
+	fs.CountP("verbose", "v", "verbosity")
+
+	var cv customValue
+	fs.Var(&cv, "custom", "custom Value implementation")
+
+	cv2 := customValue(10)
+	fs.VarP(&cv2, "customP", "", "a VarP with default")
+
+	fs.PrintDefaults()
+	got := buf.String()
+	if got != defaultOutputWithZeroValue {
+		fmt.Println("\n" + got)
+		fmt.Println("\n" + defaultOutputWithZeroValue)
+		t.Errorf("got %q want %q\n", got, defaultOutputWithZeroValue)
+	}
+}
+
 func TestVisitAllFlagOrder(t *testing.T) {
 	fs := NewFlagSet("TestVisitAllFlagOrder", ContinueOnError)
 	fs.SortFlags = false