more nuanced handling of usage message to allow user control.

also print argv(0) in default message

R=gri
DELTA=37  (21 added, 9 deleted, 7 changed)
OCL=15540
CL=15554

diff --git a/src/lib/flag.go b/src/lib/flag.go
index 351159c179e54968791710ecc7850ac6d0511ba9..3d6496ce3972777842f65acef9b58d9e9d7c6e81 100644 (file)
--- a/src/lib/flag.go
+++ b/src/lib/flag.go
@@ -287,15 +287,6 @@ type Flags struct {
        flag_list       *Flag;  // BUG: remove when we can iterate over maps
 }
 
-func (flags *Flags) Usage() {
-       // BUG: use map iteration when available
-       print("Usage: \n");
-       for f := flags.flag_list; f != nil; f = f.next {
-               print("  -", f.name, "=", f.value.Str(), ": ", f.usage, "\n");
-       }
-       sys.exit(1);
-}
-
 // --Customer's value getters
 func (f *Flag) BVal() bool {
        if !f.value.IsBool() {
@@ -328,6 +319,27 @@ func New() *Flags {
 
 var flags *Flags = New();
 
+export func PrintDefaults() {
+       // BUG: use map iteration when available
+       for f := flags.flag_list; f != nil; f = f.next {
+               print("  -", f.name, "=", f.value.Str(), ": ", f.usage, "\n");
+       }
+}
+
+export func Usage() {
+       if sys.argc() > 0 {
+               print("Usage of ", sys.argv(0), ": \n");
+       } else {
+               print("Usage: \n");
+       }
+       PrintDefaults();
+       sys.exit(1);
+}
+
+export func NFlag() int {
+       return len(flags.actual)
+}
+
 export func Arg(i int) string {
        i += flags.first_arg;
        if i < 0 || i >= sys.argc() {
@@ -391,7 +403,7 @@ func (f *Flags) ParseOne(index int) (ok bool, next int)
        name := s[num_minuses : len(s)];
        if len(name) == 0 || name[0] == '-' || name[0]=='=' {
                print("bad flag syntax: ", s, "\n");
-               f.Usage();
+               Usage();
        }
 
        // it's a flag. does it have an argument?
@@ -408,13 +420,13 @@ func (f *Flags) ParseOne(index int) (ok bool, next int)
        flag, alreadythere := flags.actual[name];
        if alreadythere {
                print("flag specified twice: -", name, "\n");
-               f.Usage();
+               Usage();
        }
        m := flags.formal;
        flag, alreadythere = m[name]; // BUG
        if !alreadythere {
                print("flag provided but not defined: -", name, "\n");
-               f.Usage();
+               Usage();
        }
        if !has_value && index < sys.argc()-1 && flag.value.ValidValue(sys.argv(index+1)) {
                // value is the next arg
@@ -428,7 +440,7 @@ func (f *Flags) ParseOne(index int) (ok bool, next int)
                                k, ok := atob(value);
                                if !ok {
                                        print("invalid boolean value ", value, " for flag: -", name, "\n");
-                                       f.Usage();
+                                       Usage();
                                }
                                flag.value.AsBool().Set(k)
                        } else {
@@ -437,18 +449,18 @@ func (f *Flags) ParseOne(index int) (ok bool, next int)
                case flag.value.IsInt():
                        if !has_value {
                                print("flag needs an argument: -", name, "\n");
-                               f.Usage();
+                               Usage();
                        }
                        k, ok := atoi(value);
                        if !ok {
                                print("invalid integer value ", value, " for flag: -", name, "\n");
-                               f.Usage();
+                               Usage();
                        }
                        flag.value.AsInt().Set(k)
                case flag.value.IsString():
                        if !has_value {
                                print("flag needs an argument: -", name, "\n");
-                               f.Usage();
+                               Usage();
                        }
                        flag.value.AsString().Set(value)
        }