Merge pull request #250 from lovoo/streams-helper

added strings to streams helper

graph.go

@@ -384,3 +384,15 @@ func tableName(group Group) string {
 func loopName(group Group) string {
 	return string(group) + loopSuffix
 }
+
+// StringsToStreams is a simple cast/conversion functions that allows to pass a slice
+// of strings as a slice of Stream (Streams)
+// Avoids the boilerplate loop over the string array that would be necessary otherwise.
+func StringsToStreams(strings ...string) Streams {
+	streams := make(Streams, 0, len(strings))
+
+	for _, str := range strings {
+		streams = append(streams, Stream(str))
+	}
+	return streams
+}

graph_test.go

@@ -157,3 +157,26 @@ func TestGroupGraph_Inputs(t *testing.T) {
 	test.AssertEqual(t, topics.Topic(), "a,b,c")
 	test.AssertTrue(t, strings.Contains(topics.String(), "a,b,c/*codec.String"))
 }
+
+func TestStringsToStreams(t *testing.T) {
+	inputTopics := []string{"input1",
+		"input2",
+	}
+
+	streams := StringsToStreams(inputTopics...)
+	test.AssertEqual(t, streams[0], Stream("input1"))
+	test.AssertEqual(t, streams[1], Stream("input2"))
+}
+
+func ExampleStringsToStreams() {
+	inputTopics := []string{"input1",
+		"input2",
+		"input3",
+	}
+
+	// use it, e.g. in the Inputs-Edge in the group graph
+	graph := DefineGroup("group",
+		Inputs(StringsToStreams(inputTopics...), new(codec.String), func(ctx Context, msg interface{}) {}),
+	)
+	_ = graph
+}