enforce unique names

Signed-off-by: Jeff Carr <jcarr@wit.com>

example/main.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"go.wit.com/lib/protobuf/zoopb"
+	"go.wit.com/log"
 )
 
 func main() {
@@ -11,10 +12,29 @@ func main() {
 	all = new(zoopb.Packages)
 	// r = zoopb.LoadJSON("go.wit.com/lib/protobuf/zoopb")
 
-	newP := new(zoopb.Package)
-	newP.Name = "bash"
-	newP.Version = "5.2.21"
-	all.Append(newP)
+	new1 := new(zoopb.Package)
+	new1.Name = "bash"
+	new1.Version = "5.2.21"
+	if all.Append(new1) {
+		log.Info("added", new1.Name, "ok")
+	} else {
+		log.Info("added", new1.Name, "failed")
+	}
+
+	new2 := new(zoopb.Package)
+	new2.Name = "go-clone"
+	new2.Version = "0.6.8" // good version of the macos
+	if all.Append(new2) {
+		log.Info("added", new2.Name, "ok")
+	} else {
+		log.Info("added", new2.Name, "failed")
+	}
+
+	if all.Append(new2) {
+		log.Info("added", new2.Name, "ok (this is bad)")
+	} else {
+		log.Info("added", new2.Name, "failed (but ok)")
+	}
 
 	fmt.Println("packages are:", len(all.Packages))
 }

packages.go

@@ -70,12 +70,33 @@ func (r *Packages) SortByName() *PackageIterator {
 	return iterator
 }
 
-// should this be a pointer? what really happens here?
-func (r *Packages) Append(newP *Package) {
+// enforces no duplicate package names
+func (r *Packages) Append(newP *Package) bool {
 	lock.Lock()
 	defer lock.Unlock()
 
+	for _, p := range r.Packages {
+		if p.Name == newP.Name {
+			return false
+		}
+	}
+
 	r.Packages = append(r.Packages, newP) 
+	return true
+}
+
+// find a package by name
+func (r *Packages) FindByName(name string) *Package {
+	lock.Lock()
+	defer lock.Unlock()
+
+	for _, p := range r.Packages {
+		if p.Name == name {
+			return p
+		}
+	}
+
+	return nil
 }
 
 type ByName []*Package