C++ EventEmitter example.

Author: bnoordhuis

.gitignore

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+.lock-wscript
+build/

README.md

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+Example add-on that demonstrates how to emit events from C++ land.

event-emitter.cc

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+/*
+ * Copyright (c) 2011, Ben Noordhuis <info@bnoordhuis.nl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <v8.h>
+#include <node.h>
+
+using namespace v8;
+using namespace node;
+
+namespace {
+
+struct Emitter: ObjectWrap {
+  static Handle<Value> New(const Arguments& args);
+  static Handle<Value> Ping(const Arguments& args);
+};
+
+
+Handle<Value> Emitter::New(const Arguments& args) {
+  HandleScope scope;
+
+  assert(args.IsConstructCall());
+  Emitter* self = new Emitter();
+  self->Wrap(args.This());
+
+  return scope.Close(args.This());
+}
+
+
+// emits ping event
+Handle<Value> Emitter::Ping(const Arguments& args) {
+  HandleScope scope;
+
+  Local<Value> emit_v = args.This()->Get(String::NewSymbol("emit"));
+  assert(emit_v->IsFunction());
+  Local<Function> emit_f = emit_v.As<Function>();
+
+  Handle<Value> argv[2] = {
+    String::New("ping"), // event name
+    args[0]->ToString()  // argument
+  };
+
+  TryCatch tc;
+
+  emit_f->Call(args.This(), 2, argv);
+
+  if (tc.HasCaught())
+    FatalException(tc);
+
+  return Undefined();
+}
+
+
+extern "C" void init(Handle<Object> target) {
+  HandleScope scope;
+
+  Local<FunctionTemplate> t = FunctionTemplate::New(Emitter::New);
+  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->SetClassName(String::New("Emitter"));
+  NODE_SET_PROTOTYPE_METHOD(t, "ping", Emitter::Ping);
+
+  target->Set(String::NewSymbol("Emitter"), t->GetFunction());
+}
+
+} // anonymous namespace

event-emitter.js

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+/*
+ * Copyright (c) 2011, Ben Noordhuis <info@bnoordhuis.nl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+// javascript shim that lets our object inherit from EventEmitter
+var Emitter = require(__dirname + '/build/Release/event-emitter.node').Emitter;
+var events = require('events');
+
+inherits(Emitter, events.EventEmitter);
+exports.Emitter = Emitter;
+
+// extend prototype
+function inherits(target, source) {
+  for (var k in source.prototype)
+    target.prototype[k] = source.prototype[k];
+}

test.js

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+/*
+ * Copyright (c) 2011, Ben Noordhuis <info@bnoordhuis.nl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+var Emitter = require('./event-emitter').Emitter;
+
+var e = new Emitter();
+
+e.on('ping', function(s) {
+  console.error('You say ping, I say %s.', s);
+});
+
+// emits a 'ping' event from c++ land
+e.ping('pong');

wscript

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+def set_options(ctx):
+	ctx.tool_options('compiler_cxx')
+
+def configure(ctx):
+	ctx.check_tool('compiler_cxx')
+	ctx.check_tool('node_addon')
+
+def build(ctx):
+	t = ctx.new_task_gen('cxx', 'shlib', 'node_addon')
+	t.target = 'event-emitter'
+	t.source = 'event-emitter.cc'