flag: make zero FlagSet useful
This makes it possible to use a FlagSet as a
field in a larger struct.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5036041
diff --git a/src/pkg/flag/flag.go b/src/pkg/flag/flag.go
index 38b65d1..f13f7a4 100644
--- a/src/pkg/flag/flag.go
+++ b/src/pkg/flag/flag.go
@@ -286,6 +286,9 @@
if !ok {
return false
}
+ if f.actual == nil {
+ f.actual = make(map[string]*Flag)
+ }
f.actual[name] = flag
return true
}
@@ -559,6 +562,9 @@
fmt.Fprintf(os.Stderr, "%s flag redefined: %s\n", f.name, name)
panic("flag redefinition") // Happens only if flags are declared with identical names
}
+ if f.formal == nil {
+ f.formal = make(map[string]*Flag)
+ }
f.formal[name] = flag
}
@@ -586,6 +592,8 @@
func (f *FlagSet) usage() {
if f == commandLine {
Usage()
+ } else if f.Usage == nil {
+ defaultUsage(f)
} else {
f.Usage()
}
@@ -657,6 +665,9 @@
return false, f.failf("invalid value %q for flag: -%s", value, name)
}
}
+ if f.actual == nil {
+ f.actual = make(map[string]*Flag)
+ }
f.actual[name] = flag
return true, nil
}
@@ -713,10 +724,15 @@
func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet {
f := &FlagSet{
name: name,
- actual: make(map[string]*Flag),
- formal: make(map[string]*Flag),
errorHandling: errorHandling,
}
- f.Usage = func() { defaultUsage(f) }
return f
}
+
+// Init sets the name and error handling property for a flag set.
+// By default, the zero FlagSet uses an empty name and the
+// ContinueOnError error handling policy.
+func (f *FlagSet) Init(name string, errorHandling ErrorHandling) {
+ f.name = name
+ f.errorHandling = errorHandling
+}
diff --git a/src/pkg/flag/flag_test.go b/src/pkg/flag/flag_test.go
index 19c0dea..f135316 100644
--- a/src/pkg/flag/flag_test.go
+++ b/src/pkg/flag/flag_test.go
@@ -180,7 +180,8 @@
}
func TestUserDefined(t *testing.T) {
- flags := NewFlagSet("test", ContinueOnError)
+ var flags FlagSet
+ flags.Init("test", ContinueOnError)
var v flagVar
flags.Var(&v, "v", "usage")
if err := flags.Parse([]string{"-v", "1", "-v", "2", "-v=3"}); err != nil {
