edifice-facade - npm Package Compare versions

Comparing version 0.2.0 to 0.3.0

lib/facade.js

@@ -1,40 +0,37 @@
-var util = require("util"),
-    EventEmitter = require("events").EventEmitter;
+module.exports = Facade;
+Facade.Facade = Facade;
 
-util.inherits(Facade, EventEmitter);
-module.exports.Facade = Facade;
+function Facade(core, permissions) {
 
-function Facade(core, actions, listeners) {
-    var thisFacade = this;
+  // Pass this to all events so that this facade knows its own events.
+  var identifier = new FacadeIdentifier();
 
-    actions = actions || [];
-    listeners = listeners || [];
+  permissions = permissions || {};
 
-    pipeEvents(actions, this, core);
-    pipeEvents(listeners, core, this).forEach(function (fn) {
-        // so that core can find events by facade
-        fn.facade = thisFacade;
+  this.emit = function (eventName) {
+    if (permissions.emit && permissions.emit.indexOf(eventName) === -1) {
+      throw new Error("Event '" + eventName + "' not in 'emit' array");
+    }
+    core.emit.apply(
+      core, Array.from(arguments).concat(identifier));
+  };
+  this.on = function (eventName, cb) {
+    if (permissions.on && permissions.on.indexOf(eventName) === -1) {
+      throw new Error("Event '" + eventName + "' not in 'on' array");
+    }
+    core.on(eventName, function () {
+      var idFlag;
+      if (arguments[arguments.length - 1] === identifier) {
+        return;
+      }
+      if (arguments[arguments.length - 1] instanceof FacadeIdentifier) {
+        idFlag = -1;
+      }
+      cb.apply(null, Array.from(arguments).slice(0, idFlag));
     });
+  };
 }
 
-function pipeEvents(eventList, origin, destination) {
-    return eventList.map(function (event) {
-        origin.on(event, handler);
-        return handler;
-
-        function handler() {
-            var backup = origin.listeners(event);
-
-            // prevent infinite recursion
-            origin.removeAllListeners(event);
-
-            destination.emit.apply(destination,
-                Array.prototype.concat.apply([event], arguments));
-
-            // restore backup
-            backup.forEach(function (listener) {
-                origin.on(event, listener);
-            });
-        }
-    });
-}
+// Make all identifiers instances of the same class so that they can be
+// identified and stripped out of events.
+function FacadeIdentifier () {}

package.json

 {
   "name": "edifice-facade",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "Create facades to separate modules in your application",
@@ -32,5 +32,4 @@ "main": "lib/facade.js",
     "grunt-contrib-watch": "~0.6.1",
-    "jshint": "~2.5.0",
-    "clone": "~0.1.11"
+    "jshint": "~2.5.0"
   }
 }

README.md

 edifice-facade
 ==============
 
-Create facades to separate modules in your application
+Create facades to separate modules in your application.
 
 Facades rely on a core which can be as simple as an EventEmitter. They separate
-modules from each other, so that the modules communicate with each other using
-events.
+modules from each other, and the modules communicate using events. It also
+enhances internal application security, ensuring nothing has more in scope than
+it needs.
 
-````
+````js
 var EventEmitter = require("events").EventEmitter,
@@ -16,13 +17,49 @@ Facade = require("edifice-facade");
 
-var fileInterfaceFacade = new Facade(core,
-    ['fileDataRead', 'fileWritten'], // permitted actions
-    ['newInputData'] // permitted listeners
-);
-var userInterfaceFacade = new Facade(core,
-    ['newInputData'],
-    ['fileDataRead', 'fileWritten']
-);
+var timerFacade = new Facade(core);
+var userInterfaceFacade = new Facade(core);
 ````
 
-Now pass these facades to your `fileInterface` and `userInterface`, so they
+Now pass these facades to your `timer` and `userInterface`, so they
 don't need to have each other or the core itself in scope.
+
+````js
+function userInterface(facade) {
+  timerUserEntry.onchange = function () {
+    facade.emit('timerValueChange', this.value);
+  };
+  facade.on('timerValueChange', function (timerVal) {
+    timerUserEntry.value = timerVal;
+  });
+}
+````
+Facades don't respond to their own events, only events from other facades,
+allowing the same data to be updated and read my multiple sources, while
+preventing loops or awkward if statements.
+
+Module permissions
+------------------
+Facades can be restricted in what events they can send and receive.
+
+````js
+var fileSystemFacade = new Facade(core, {
+  emit : ['writeSuccess', 'fileContents'],
+  on : ['save', 'read']
+});
+
+// This line will throw an error, as fileSystemFacade doesn't have receive (on)
+// permissions on userInteraction.
+fileSystemFacade.on('userInteraction', function () { ... });
+
+// This line will also throw, as fileSystemFacade doesn't have send (emit)
+// permissions on save. It should be doing the saving!
+fileSystemFacade.emit('save', data);
+````
+
+Why the name edifice-facade?
+----------------------------
+I originally planned on making a module called edifice as the core, then
+realised the core could just be a plain old EventEmitter. So ediface is no more.
+
+License
+-------
+MIT.

test/testFacade.js

 var clone = require("clone"),
-    EventEmitter = require("events").EventEmitter,
-    expect = require("expect.js"),
-    injectr = require("injectr"),
-    pretendr = require("pretendr");
+  EventEmitter = require("events").EventEmitter,
+  expect = require("expect.js"),
+  injectr = require("injectr"),
+  pretendr = require("pretendr");
 
 describe("Facade", function () {
-    var Facade,
-        mockCore,
-        core,
-        coreListener;
+  var Facade,
+    core,
+    coreListener;
+  beforeEach(function () {
+    core = new EventEmitter();
+    coreListener = pretendr(function () {});
+    core.on("a", coreListener.mock);
+  });
+  describe("#emit", function () {
     beforeEach(function () {
-        core = new EventEmitter();
-        coreListener = pretendr(function () {});
-        core.on("a", coreListener.mock);
+      Facade = injectr("../lib/facade.js").Facade;
     });
-    it("inherits EventEmitter", function () {
-        var requires;
-        requires = pretendr({
-            util : {
-                inherits : function () {}
-            },
-            events : {
-                EventEmitter : function () {}
-            }
-        });
-        Facade = injectr("../lib/facade.js", requires.mock).Facade;
-        expect(requires.util.inherits.calls).to.have.length(1);
-        expect(requires.util.inherits.calls[0].args)
-            .to.have.property(0, Facade)
-            .and.to.have.property(1, requires.events.EventEmitter.mock);
+    it("passes events to the core", function () {
+      var facade = new Facade(core);
+      facade.emit("a");
+      expect(coreListener.calls).to.have.length(1);
     });
-    it("makes the array properties optional", function () {
-        Facade = injectr("../lib/facade.js").Facade;
-        expect(function () {
-            new Facade(new EventEmitter());
-        }).to.not.throwException();
+    it("passes arguments to the core", function () {
+      var eventData = [{}, {}, {}],
+        facade = new Facade(core);
+      facade.emit("a", eventData[0], eventData[1], eventData[2]);
+      expect(coreListener.calls[0].args[0]).to.equal(eventData[0]);
+      expect(coreListener.calls[0].args[1]).to.equal(eventData[1]);
+      expect(coreListener.calls[0].args[2]).to.equal(eventData[2]);
     });
-
-    describe("#emit", function () {
-        beforeEach(function () {
-            Facade = injectr("../lib/facade.js").Facade;
-        });
-        it("passes emits to the core for listed actions", function () {
-            var eventData = {},
-                facade = new Facade(core, ["a"], []);
-            facade.emit("a", eventData);
-            expect(coreListener.calls).to.have.length(1);
-            expect(coreListener.calls[0].args)
-                .to.have.property(0, eventData);
-        });
-        it("passes emits to the core with no data", function () {
-            var facade = new Facade(core, ["a"], []);
-            facade.emit("a");
-            expect(coreListener.calls).to.have.length(1);
-            expect(coreListener.calls[0].args).to.have.length(0);
-        });
-        it("doesn't emit multiple times", function () {
-            var facade = new Facade(core, ["a"], ["a"]),
-                listener = pretendr(function () {});
-            facade.on("a", listener.mock);
-            facade.emit("a", {});
-            expect(coreListener.calls).to.have.length(1);
-            expect(listener.calls).to.have.length(1);
-        });
-        it("doesn't disrupt the listeners on itself", function () {
-            var e,
-                facade = new Facade(core, ["a"], ["a", "b"]);
-            ["a", "a", "b"].forEach(function (e) {
-                facade.on(e, function () {});
-            });
-            e = clone(facade._events);
-            facade.emit("a");
-            expect(facade._events).to.eql(e);
-        });
-        it("doesn't pass emits of non-listed actions", function () {
-            var facade = new Facade(core, ["c"], []);
-            facade.emit("a", {});
-            expect(coreListener.calls).to.have.length(0);
-        });
-        it("passes multiple arguments to the core", function () {
-            var facade = new Facade(core, ["a"], []);
-            facade.emit("a", "b", "c");
-            expect(coreListener.calls).to.have.length(1);
-            expect(coreListener.calls[0].args)
-                .to.have.property(0, "b")
-                .and.to.have.property(1, "c");
-        });
+    it("throws an error when events aren't in the emit array", function () {
+      var facade = new Facade(core, {
+        emit : []
+      });
+      expect(function () {
+        facade.emit('a');
+      }).to.throwError(/Event 'a' not in 'emit' array/);
     });
-
-    describe("#on", function () {
-        beforeEach(function () {
-            Facade = injectr("../lib/facade.js").Facade;
-            mockCore = pretendr({
-                on : function () {},
-                emit : function () {}
-            });
-        });
-        it("passes handlers to the core for listed listeners", function () {
-            var fn = pretendr(function () {}),
-                facade = new Facade(core, [], ["b"]);
-            facade.on("b", fn.mock);
-            expect(core.listeners("b")).to.have.length(1);
-            core.emit("b", "foo");
-            expect(fn.calls).to.have.length(1);
-            expect(fn.calls[0].args).to.have.property(0, "foo");
-        });
-        it("doesn't pass handlers for non-listed listeners", function () {
-            var facade = new Facade(core, [], ["b"]),
-                listener = pretendr(function () {});
-            facade.on("c", listener.mock);
-            core.emit("c");
-            expect(listener.calls).to.have.length(0);
-        });
-        it("adds the facade as a property of the handler", function () {
-            var facade = new Facade(core, [], ["b"]);
-            facade.on("b", function () {});
-            expect(core.listeners("b")[0])
-                .to.have.property("facade", facade);
-        });
+    it("doesn't throw an error when events are in the emit array", function () {
+      var facade = new Facade(core, {
+        emit : ['a']
+      });
+      expect(function () {
+        facade.emit('a');
+      }).not.to.throwError();
     });
-});
+  });
+  describe("#on", function () {
+    var listener;
+    beforeEach(function () {
+      Facade = injectr("../lib/facade.js").Facade;
+      listener = pretendr(function () {});
+    });
+    it("listens for events on the core", function () {
+      var facade = new Facade(core);
+      facade.on('b', listener.mock);
+      core.emit('b');
+      expect(listener.calls).to.have.length(1);
+    });
+    it("does not listen for events created by own emit", function () {
+      var facade = new Facade(core);
+      facade.on('c', listener.mock);
+      facade.emit('c');
+      expect(listener.calls).to.have.length(0);
+    });
+    it("has arguments passed from the core", function () {
+      var arg = {},
+        facade = new Facade(core);
+      facade.on('c', listener.mock);
+      core.emit('c', arg);
+      expect(listener.calls[0].args[0]).to.equal(arg);
+    });
+    it("throws an error when events aren't in the 'on' array", function () {
+      var facade = new Facade(core, {
+        on : []
+      });
+      expect(function () {
+        facade.on('a');
+      }).to.throwError(/Event 'a' not in 'on' array/);
+    });
+    it("doesn't throw an error when events are in the 'on' array", function () {
+      var facade = new Facade(core, {
+        on : ['a']
+      });
+      expect(function () {
+        facade.on('a');
+      }).not.to.throwError();
+    });
+  });
+  describe("pair of facades", function () {
+    var facades,
+      listener;
+    beforeEach(function () {
+      Facade = injectr("../lib/facade.js").Facade;
+      listener = pretendr(function () {});
+      facades = [new Facade(core), new Facade(core)];
+    });
+    it("will pass arguments exactly between them", function () {
+      var args = [{}, [], '3'];
+      facades[0].on('a', listener.mock);
+      facades[1].emit('a', args[0], args[1], args[2]);
+      expect(listener.calls[0].args)
+        .to.have.length(args.length)
+        .and.to.have.property(0, args[0])
+        .and.to.have.property(1, args[1])
+        .and.to.have.property(2, args[2]);
+    });
+  });
+});

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