Merge pull request #78 from moorereason/go1.7-zerovalues
Fix default value detection for Go 1.7
diff --git a/.travis.yml b/.travis.yml
index 580ad22..0a7c136 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,8 +5,12 @@
go:
- 1.5.4
- 1.6.3
+ - 1.7
- tip
+matrix:
+ allow_failures:
+ - go: tip
install:
- go get github.com/golang/lint/golint
- export PATH=$GOPATH/bin:$PATH
diff --git a/flag.go b/flag.go
index 708651e..eb143d7 100644
--- a/flag.go
+++ b/flag.go
@@ -419,20 +419,26 @@
fmt.Fprintf(f.out(), "%s", usages)
}
-// isZeroValue guesses whether the string represents the zero
-// value for a flag. It is not accurate but in practice works OK.
-func isZeroValue(value string) bool {
- switch value {
- case "false":
- return true
- case "<nil>":
- return true
- case "":
- return true
- case "0":
+// defaultIsZeroValue returns true if the default value for this flag represents
+// a zero value.
+func (f *Flag) defaultIsZeroValue() bool {
+ switch f.Value.(type) {
+ case boolFlag:
+ return f.DefValue == "false"
+ case *durationValue:
+ // Beginning in Go 1.7, duration zero values are "0s"
+ return f.DefValue == "0" || f.DefValue == "0s"
+ case *intValue, *int8Value, *int32Value, *int64Value, *uintValue, *uint8Value, *uint16Value, *uint32Value, *uint64Value, *countValue, *float32Value, *float64Value:
+ return f.DefValue == "0"
+ case *stringValue:
+ return f.DefValue == ""
+ case *ipValue, *ipMaskValue, *ipNetValue:
+ return f.DefValue == "<nil>"
+ case *intSliceValue, *stringSliceValue:
+ return f.DefValue == "[]"
+ default:
return true
}
- return false
}
// UnquoteUsage extracts a back-quoted name from the usage
@@ -516,7 +522,7 @@
}
line += usage
- if !isZeroValue(flag.DefValue) {
+ if !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
index 0ae2e4f..86b37e5 100644
--- a/flag_test.go
+++ b/flag_test.go
@@ -13,6 +13,7 @@
"os"
"reflect"
"sort"
+ "strconv"
"strings"
"testing"
"time"
@@ -873,19 +874,38 @@
}
}
-const defaultOutput = ` --A for bootstrapping, allow 'any' type
- --Alongflagname disable bounds checking
- -C, --CCC a boolean defaulting to true (default true)
- --D path set relative path for local imports
- --F number a non-zero number (default 2.7)
- --G float a float that defaults to zero
- --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)
- --Z int an int that defaults to zero
- --maxT timeout set timeout for dial
+const defaultOutput = ` --A for bootstrapping, allow 'any' type
+ --Alongflagname disable bounds checking
+ -C, --CCC a boolean defaulting to true (default true)
+ --D path set relative path for local imports
+ --F number a non-zero number (default 2.7)
+ --G float a float that defaults to zero
+ --IP ip IP address with no default
+ --IPMask ipMask Netmask address with no default
+ --IPNet ipNet IP network with no default
+ --Ints intSlice int slice with zero 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)
+ --Strings stringSlice string slice with zero default
+ --Z int an int that defaults to zero
+ --custom custom custom Value implementation
+ --maxT timeout set timeout for dial
`
+// Custom value that satisfies the Value interface.
+type customValue int
+
+func (cv *customValue) String() string { return fmt.Sprintf("%v", *cv) }
+
+func (cv *customValue) Set(s string) error {
+ v, err := strconv.ParseInt(s, 0, 64)
+ *cv = customValue(v)
+ return err
+}
+
+func (cv *customValue) Type() string { return "custom" }
+
func TestPrintDefaults(t *testing.T) {
fs := NewFlagSet("print defaults test", ContinueOnError)
var buf bytes.Buffer
@@ -897,12 +917,21 @@
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.StringSlice("Strings", []string{}, "string slice with zero default")
+
+ var cv customValue
+ fs.Var(&cv, "custom", "custom Value implementation")
+
fs.PrintDefaults()
got := buf.String()
if got != defaultOutput {
