eventbus: make it usable and add README

examples/eventbus/.gitignore

@@ -0,0 +1 @@
+eventbus

examples/eventbus/eventbus.v

@@ -0,0 +1,16 @@
+module main
+
+import (
+	some_module
+	eventbus
+)
+
+fn main(){
+	mut sub := some_module.get_subscriber()
+	sub.subscribe("error", on_error)
+	some_module.do_work()
+}
+
+fn on_error(p eventbus.Params) {
+	println(p.get_string("error"))
+}

examples/eventbus/some_module/some_module.v

@@ -0,0 +1,27 @@
+module some_module
+
+import (
+	eventbus
+)
+
+const (
+	eb = eventbus.new()
+)
+
+pub fn do_work(){
+	mut params := eventbus.Params{}
+	for i in 0..20 {
+		println("working...")
+		if i == 15 {
+			params.put_string("error", "CRASH!!")
+			eb.publish("error", params)
+			eb.publish("error", params)
+			return
+		}
+	}
+	
+}
+
+pub fn get_subscriber() eventbus.Subscriber {
+	return eb.subscriber
+}

tools/vtest.v

@@ -165,7 +165,7 @@ pub fn v_test_v(args_before_test string){
 	println('\nBuilding examples...')
 	mut es := new_test_sesion( args_before_test )
 	files := os.walk_ext(parent_dir+'/examples','.v')
-	stable := files.filter(!it.contains('automaton.v'))
+	stable := files.filter(!it.contains('automaton.v') && !it.contains('some_module.v'))
 	es.files << stable
 	es.test()
 	println( es.benchmark.total_message('building examples') )

vlib/eventbus/README.md

@@ -0,0 +1,126 @@
+# Event Bus
+
+A module to provide eventing capabilities using pub/sub.
+
+## API
+
+1. `new()` - create a new `EventBus`
+
+### Structs:
+
+**EventBus:**
+
+1. `publish(string, Params)` - publish an event with provided Params & name
+2. `clear_all()` - clear all subscribers
+3. `has_subscriber(string)` - check if a subscriber to an event exists
+
+**Subscriber:**
+
+1. `subscribe(string, fn(Params))` - subscribe to an event
+2. `subscribe_once(string, fn(Params))` - subscribe only once to an event
+3. `is_subscribed(string)` - check if we are subscribed to an event
+4. `unsubscribe(string)` - unsubscribe from an event
+
+**Event Handler Signature:**
+
+The function given to `subscribe` and `subscribe_once` must match this:
+
+```v
+fn(Params){
+
+}
+// Example
+fn onPress(p Params){
+    //your code here...
+}
+```
+
+## Usage
+
+For **usage across modules** [check the example](https://github.com/vlang/v/tree/master/examples/eventbus).
+
+_Note: As a general rule, you will need to **subscribe before emitting**._
+
+**main.v**
+
+```v
+module main
+import eventbus
+
+// initialize it globally
+const (
+    eb = eventbus.new()
+)
+
+fn main(){
+    // get a mutable reference to the subscriber
+	mut sub := eb.subscriber
+    // subscribe to the 'error' event
+	sub.subscribe("error", on_error)
+    // start the work
+	do_work()
+}
+
+// the event handler
+fn on_error(p eventbus.Params) {
+	println(p.get_string("error"))
+}
+```
+
+**work.v**
+
+```v
+module main
+
+import (
+	eventbus
+)
+
+fn do_work(){
+    // get a mutable Params instance & put some data into it
+	mut params := eventbus.Params{}
+    params.put_string("error", "Error: no internet connection.")
+    // publish the event
+    eb.publish("error", params)
+}
+```
+
+### How to use `Params`:
+
+```v
+mut params := eventbus.Params{}
+params.put_string("string", "vevent")
+params.put_int("int", 20)
+params.put_bool("bo", true)
+//the array  & map currently needs to set like this
+eventbus.put_array(mut params, "array", [1,2,3])
+eventbus.put_map(mut params, "map", "", {"hello": "world"})
+
+params.get_string("string") == "vevent"
+params.get_int("int") == 20
+params.get_bool("bo") == true
+m := params.get_string_map("map")
+//the array currently needs to gotten like this
+arr := eventbus.get_array(params, "array", 0)
+
+//you can also pass around custom type arrays & maps (it's a little crude but works):
+struct Example{}
+custom_map := {"example": Example{}}
+eventbus.put_map(mut params, "custom_map", Example{}, custom_map)
+//and get it like this
+eventbus.get_map(params, "custom_map", {"":Example{}}
+
+//For arrays:
+eventbus.put_array(mut params, "array", [Example{}])
+eventbus.get_array(params, "custom_array", Example{})
+```
+
+### Notes:
+
+1. Each `EventBus` instance has it's own registry (i.e. there is no global event registry so you can't just subscribe to an event wherever you are.
+2. Each `EventBus` has a `Subscriber` instance which will need to be either exposed or you can make small public helper functions specific to your module like (`onPress`, `onError`) and etc.
+3. The `eventbus` module has some helpers to ease getting/setting of Params (since V doesn't support empty interfaces yet or reflection) so use them (see usage above).
+
+**The rationale behind separating Subscriber & Emitter:**
+
+This is mainly for security because the if emitter & subscriber are both passed around, a client can easily emit events acting as the server. So a client should only be able to use the Subscriber methods.

vlib/eventbus/eventbus.v

@@ -1,9 +1,16 @@
 module eventbus
 
+
+pub struct Publisher {
+	mut:
+	registry &Registry
+}
+
 pub struct Subscriber {
 	mut:
 	registry &Registry
 }
+
 struct Registry{
 	mut:
 	names []string
@@ -18,12 +25,11 @@ struct EventHandler {
 pub struct EventBus{
 	mut:
 	registry &Registry
+	publisher &Publisher
 	pub:
-	subscriber Subscriber
+	subscriber &Subscriber
 }
 
-// EventBus Methods
-
 pub fn new() &EventBus{
 	registry := &Registry{
 		names: []
@@ -32,35 +38,50 @@ pub fn new() &EventBus{
 	}
 	return &EventBus{
 		registry,
-		Subscriber{registry}
+		&Publisher{registry},
+		&Subscriber{registry}
 	}
 }
 
-pub fn (eb mut EventBus) publish(name string, p Params){
-	for i, n in eb.registry.names {
+// EventBus Methods
+
+pub fn (eb &EventBus) publish(name string, p Params) {
+	mut publisher := eb.publisher
+	publisher.publish(name, p)
+}
+
+pub fn (eb &EventBus) clear_all(){
+	mut publisher := eb.publisher
+	publisher.clear_all()
+}
+
+pub fn (eb &EventBus) has_subscriber(name string) bool {
+	return eb.registry.check_subscriber(name)
+}
+
+// Publisher Methods
+
+fn (pb mut Publisher) publish(name string, p Params){
+	for i, n in pb.registry.names {
 		if name == n {
-			eh := eb.registry.events[i]
+			eh := pb.registry.events[i]
 			invoke(eh, p)
-			once_index := eb.registry.once.index(eb.registry.names[i])
+			once_index := pb.registry.once.index(pb.registry.names[i])
 			if once_index > -1 {
-				eb.registry.events.delete(i)
-				eb.registry.names.delete(i)
-				eb.registry.once.delete(once_index)
+				pb.registry.events.delete(i)
+				pb.registry.names.delete(i)
+				pb.registry.once.delete(once_index)
 			}
 		}
 	}
 }
 
-pub fn (eb mut EventBus) clear_all(){
-	for i, n in eb.registry.names {
-		eb.registry.delete_entry(i)
+fn (p mut Publisher) clear_all(){
+	for i, n in p.registry.names {
+		p.registry.delete_entry(i)
 	}
 }
 
-pub fn (eb &EventBus) has_subscriber(name string) bool {
-	return eb.registry.check_subscriber(name)
-}
-
 // Subscriber Methods
 
 pub fn (s mut Subscriber) subscribe(name string, handler fn(Params)){