make interface to the flags themselves more public.

add visitor functions to scan the flags.
add a way to set a flag.
add a flag test.

R=rsc
DELTA=169  (99 added, 19 deleted, 51 changed)
OCL=25076
CL=25078

src/lib/flag.go

@@ -115,11 +115,13 @@ func newBoolValue(val bool, p *bool) *boolValue {
 	return &boolValue(p)
 }
 
-func (b *boolValue) set(val bool) {
-	*b.p = val;
+func (b *boolValue) set(s string) bool {
+	v, ok  := atob(s);
+	*b.p = v;
+	return ok
 }
 
-func (b *boolValue) str() string {
+func (b *boolValue) String() string {
 	return fmt.Sprintf("%v", *b.p)
 }
 
@@ -133,11 +135,13 @@ func newIntValue(val int, p *int) *intValue {
 	return &intValue(p)
 }
 
-func (i *intValue) set(val int) {
-	*i.p = val;
+func (i *intValue) set(s string) bool {
+	v, ok  := atoi(s);
+	*i.p = int(v);
+	return ok
 }
 
-func (i *intValue) str() string {
+func (i *intValue) String() string {
 	return fmt.Sprintf("%v", *i.p)
 }
 
@@ -151,11 +155,13 @@ func newInt64Value(val int64, p *int64) *int64Value {
 	return &int64Value(p)
 }
 
-func (i *int64Value) set(val int64) {
-	*i.p = val;
+func (i *int64Value) set(s string) bool {
+	v, ok := atoi(s);
+	*i.p = v;
+	return ok;
 }
 
-func (i *int64Value) str() string {
+func (i *int64Value) String() string {
 	return fmt.Sprintf("%v", *i.p)
 }
 
@@ -169,11 +175,13 @@ func newUintValue(val uint, p *uint) *uintValue {
 	return &uintValue(p)
 }
 
-func (i *uintValue) set(val uint) {
-	*i.p = val
+func (i *uintValue) set(s string) bool {
+	v, ok := atoi(s);	// TODO(r): want unsigned
+	*i.p = uint(v);
+	return ok;
 }
 
-func (i *uintValue) str() string {
+func (i *uintValue) String() string {
 	return fmt.Sprintf("%v", *i.p)
 }
 
@@ -187,11 +195,13 @@ func newUint64Value(val uint64, p *uint64) *uint64Value {
 	return &uint64Value(p)
 }
 
-func (i *uint64Value) set(val uint64) {
-	*i.p = val;
+func (i *uint64Value) set(s string) bool {
+	v, ok := atoi(s);	// TODO(r): want unsigned
+	*i.p = uint64(v);
+	return ok;
 }
 
-func (i *uint64Value) str() string {
+func (i *uint64Value) String() string {
 	return fmt.Sprintf("%v", *i.p)
 }
 
@@ -205,25 +215,27 @@ func newStringValue(val string, p *string) *stringValue {
 	return &stringValue(p)
 }
 
-func (s *stringValue) set(val string) {
+func (s *stringValue) set(val string) bool {
 	*s.p = val;
+	return true;
 }
 
-func (s *stringValue) str() string {
+func (s *stringValue) String() string {
 	return fmt.Sprintf("%#q", *s.p)
 }
 
-// -- Value interface
-type _Value interface {
-	str() string;
+// -- FlagValue interface
+type FlagValue interface {
+	String() string;
+	set(string) bool;
 }
 
-// -- Flag structure (internal)
+// -- Flag structure
 type Flag struct {
-	name	string;	// name as it appears on command line
-	usage	string;	// help message
-	value	_Value;	// value as set
-	defvalue	string;	// default value (as text); for usage message
+	Name	string;	// name as it appears on command line
+	Usage	string;	// help message
+	Value	FlagValue;	// value as set
+	DefValue	string;	// default value (as text); for usage message
 }
 
 type allFlags struct {
@@ -234,10 +246,45 @@ type allFlags struct {
 
 var flags *allFlags = &allFlags(make(map[string] *Flag), make(map[string] *Flag), 1)
 
-func PrintDefaults() {
+// Visit all flags, including those defined but not set.
+func VisitAll(fn func(*Flag)) {
 	for k, f := range flags.formal {
-		print("  -", f.name, "=", f.defvalue, ": ", f.usage, "\n");
+		fn(f)
+	}
+}
+
+// Visit only those flags that have been set
+func Visit(fn func(*Flag)) {
+	for k, f := range flags.actual {
+		fn(f)
+	}
+}
+
+func Lookup(name string) *Flag {
+	f, ok := flags.formal[name];
+	if !ok {
+		return nil
+	}
+	return f
+}
+
+func Set(name, value string) bool {
+	f, ok := flags.formal[name];
+	if !ok {
+		return false
+	}
+	ok = f.Value.set(value);
+	if !ok {
+		return false
 	}
+	flags.actual[name] = f;
+	return true;
+}
+
+func PrintDefaults() {
+	VisitAll(func(f *Flag) {
+		print("  -", f.Name, "=", f.DefValue, ": ", f.Usage, "\n");
+	})
 }
 
 func Usage() {
@@ -266,12 +313,9 @@ func NArg() int {
 	return len(sys.Args) - flags.first_arg
 }
 
-func add(name string, value _Value, usage string) {
-	f := new(Flag);
-	f.name = name;
-	f.usage = usage;
-	f.value = value;
-	f.defvalue = value.str();	// Remember the default value as a string; it won't change.
+func add(name string, value FlagValue, usage string) {
+	// Remember the default value as a string; it won't change.
+	f := &Flag(name, usage, value, value.String());
 	dummy, alreadythere := flags.formal[name];
 	if alreadythere {
 		print("flag redefined: ", name, "\n");
@@ -388,16 +432,14 @@ func (f *allFlags) parseOne(index int) (ok bool, next int)
 		print("flag provided but not defined: -", name, "\n");
 		Usage();
 	}
-	if f, ok := flag.value.(*boolValue); ok {
+	if f, ok := flag.Value.(*boolValue); ok {	// special case: doesn't need an arg
 		if has_value {
-			k, ok := atob(value);
-			if !ok {
+			if !f.set(value) {
 				print("invalid boolean value ", value, " for flag: -", name, "\n");
 				Usage();
 			}
-			f.set(k)
 		} else {
-			f.set(true)
+			f.set("true")
 		}
 	} else {
 		// It must have a value, which might be the next argument.
@@ -411,24 +453,10 @@ func (f *allFlags) parseOne(index int) (ok bool, next int)
 			print("flag needs an argument: -", name, "\n");
 			Usage();
 		}
-		if f, ok := flag.value.(*stringValue); ok {
-			f.set(value)
-		} else {
-			// It's an integer flag.  TODO(r): check for overflow?
-			k, ok := atoi(value);
-			if !ok {
-				print("invalid integer value ", value, " for flag: -", name, "\n");
+		ok = flag.Value.set(value);
+		if !ok {
+			print("invalid value ", value, " for flag: -", name, "\n");
 				Usage();
-			}
-			if f, ok := flag.value.(*intValue); ok {
-				f.set(int(k));
-			} else if f, ok := flag.value.(*int64Value); ok {
-				f.set(k);
-			} else if f, ok := flag.value.(*uintValue); ok {
-				f.set(uint(k));
-			} else if f, ok := flag.value.(*uint64Value); ok {
-				f.set(uint64(k));
-			}
 		}
 	}
 	flags.actual[name] = flag;

src/lib/flag_test.go

+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flag
+
+import (
+	"flag";
+	"fmt";
+	"testing";
+)
+
+var (
+	test_bool = flag.Bool("test_bool", true, "bool value");
+	test_int = flag.Int("test_int", 1, "int value");
+	test_int64 = flag.Int64("test_int64", 1, "int64 value");
+	test_uint = flag.Uint("test_uint", 1, "uint value");
+	test_uint64 = flag.Uint64("test_uint64", 1, "uint64 value");
+	test_string = flag.String("test_string", "1", "string value");
+)
+
+// Because this calls flag.Parse, it needs to be the only Test* function
+func TestEverything(t *testing.T) {
+	flag.Parse();
+	m := make(map[string] *flag.Flag);
+	visitor := func(f *flag.Flag) {
+		if len(f.Name) > 5 && f.Name[0:5] == "test_" {
+			m[f.Name] = f
+		}
+	};
+	flag.VisitAll(visitor);
+	if len(m) != 6 {
+		t.Error("flag.VisitAll misses some flags");
+		for k, v := range m {
+			t.Log(k, *v)
+		}
+	}
+	m = make(map[string] *flag.Flag);
+	flag.Visit(visitor);
+	if len(m) != 0 {
+		t.Errorf("flag.Visit sees unset flags");
+		for k, v := range m {
+			t.Log(k, *v)
+		}
+	}
+	// Now set some flags
+	flag.Set("test_bool", "false");
+	flag.Set("test_uint", "1234");
+	flag.Visit(visitor);
+	if len(m) != 2 {
+		t.Error("flag.Visit fails after set");
+		for k, v := range m {
+			t.Log(k, *v)
+		}
+	}
+}