prevent memory leaks when using multiple screens. see #157.

README.md

@@ -436,6 +436,10 @@ The screen on which every other node renders.
 - __screenshot([xi, xl, yi, yl])__ - Take an SGR screenshot of the screen
   within the region. Returns a string containing only characters and SGR codes.
   Can be displayed by simply echoing it in a terminal.
+- __destroy()__ - destroy the screen object and remove it from the global list.
+  only useful if using multiple screens.
+- __program.destroy()__ - destroy the program object and remove it from the
+  global list.  only useful if using multiple programs.
 
 
 #### Element (from Node)

lib/program.js

@@ -31,6 +31,8 @@ function Program(options) {
     return new Program(options);
   }
 
+  Program.bind(this);
+
   EventEmitter.call(this);
 
   if (!options || options.__proto__ !== Object.prototype) {
@@ -104,19 +106,6 @@ function Program(options) {
   this._buf = '';
   this._flush = this.flush.bind(this);
 
-  unshiftEvent(process, 'exit', function() {
-    // Ensure the buffer is flushed (it should
-    // always be at this point, but who knows).
-    self.flush();
-    // Ensure _exiting is set (could technically
-    // use process._exiting).
-    self._exiting = true;
-  });
-
-  if (!Program.global) {
-    Program.global = this;
-  }
-
   if (options.tput !== false) {
     this.setupTput();
   }
@@ -124,8 +113,41 @@ function Program(options) {
   this.listen();
 }
 
+Program.global = null;
+
+Program.total = 0;
+
+Program.list = [];
+
+Program.bind = function(program) {
+  if (!Program.global) {
+    Program.global = program;
+  }
+
+  if (!~Program.list.indexOf(program)) {
+    Program.list.push(program);
+    Program.total++;
+  }
+
+  if (Program._bound) return;
+  Program._bound = true;
+
+  unshiftEvent(process, 'exit', function() {
+    Program.list.forEach(function(program) {
+      // Ensure the buffer is flushed (it should
+      // always be at this point, but who knows).
+      program.flush();
+      // Ensure _exiting is set (could technically
+      // use process._exiting).
+      program._exiting = true;
+    });
+  });
+};
+
 Program.prototype.__proto__ = EventEmitter.prototype;
 
+Program.prototype.type = 'program';
+
 Program.prototype.log = function() {
   return this._log('LOG',  util.format.apply(util, arguments));
 };
@@ -272,9 +294,8 @@ Program.prototype.listen = function() {
   var keys = require('./keys')
     , self = this;
 
-  if (!this.output.isTTY) {
-    // TODO: Add an ncurses-like warning.
-  }
+  if (this.input._blessedListened) return;
+  this.input._blessedListened = true;
 
   // unshiftEvent(process, 'exit', function() {
   //   if (self._originalTitle) {
@@ -344,6 +365,9 @@ Program.prototype.listen = function() {
     }
   });
 
+  if (this.output._blessedListened) return;
+  this.output._blessedListened = true;
+
   // Output
   function resize() {
     self.cols = self.output.columns;
@@ -366,6 +390,18 @@ Program.prototype.listen = function() {
   });
 };
 
+Program.prototype.destroy = function() {
+  var index = Program.list.indexOf(this);
+  if (~index) {
+    Program.list.splice(index, 1);
+    Program.total--;
+    if (Program.total === 0) {
+      Program.global = null;
+    }
+    this.emit('destroy');
+  }
+};
+
 Program.prototype.key = function(key, listener) {
   if (typeof key === 'string') key = key.split(/\s*,\s*/);
   key.forEach(function(key) {

lib/widgets/screen.js

@@ -35,6 +35,8 @@ function Screen(options) {
     return new Screen(options);
   }
 
+  Screen.bind(this);
+
   options = options || {};
   if (options.rsety && options.listen) {
     options = { program: options };
@@ -64,10 +66,6 @@ function Screen(options) {
 
   this.tput = this.program.tput;
 
-  if (!Screen.global) {
-    Screen.global = this;
-  }
-
   Node.call(this, options);
 
   this.autoPadding = options.autoPadding !== false;
@@ -175,35 +173,6 @@ function Screen(options) {
 
   this.setMaxListeners(Infinity);
 
-  Screen.total++;
-
-  process.on('uncaughtException', function(err) {
-    if (process.listeners('uncaughtException').length > Screen.total) {
-      return;
-    }
-    self.leave();
-    err = err || new Error('Uncaught Exception.');
-    console.error(err.stack ? err.stack + '' : err + '');
-    nextTick(function() {
-      process.exit(1);
-    });
-  });
-
-  ['SIGTERM', 'SIGINT', 'SIGQUIT'].forEach(function(signal) {
-    process.on(signal, function() {
-      if (process.listeners(signal).length > Screen.total) {
-        return;
-      }
-      nextTick(function() {
-        process.exit(0);
-      });
-    });
-  });
-
-  process.on('exit', function() {
-    self.leave();
-  });
-
   this.enter();
 
   this.postEnter();
@@ -213,6 +182,59 @@ Screen.global = null;
 
 Screen.total = 0;
 
+Screen.list = [];
+
+Screen.signals = true;
+
+Screen.bind = function(screen) {
+  if (!Screen.global) {
+    Screen.global = screen;
+  }
+
+  if (!~Screen.list.indexOf(screen)) {
+    Screen.list.push(screen);
+    Screen.total++;
+  }
+
+  if (Screen._bound) return;
+  Screen._bound = true;
+
+  process.on('uncaughtException', function(err) {
+    if (process.listeners('uncaughtException').length > Screen.total) {
+      return;
+    }
+    Screen.list.slice().forEach(function(screen) {
+      screen.destroy();
+    });
+    err = err || new Error('Uncaught Exception.');
+    console.error(err.stack ? err.stack + '' : err + '');
+    nextTick(function() {
+      process.exit(1);
+    });
+  });
+
+  // XXX Multiple signal handlers and removal of signal
+  // handlers does not work, so we have this option instead.
+  if (Screen.signals) {
+    ['SIGTERM', 'SIGINT', 'SIGQUIT'].forEach(function(signal) {
+      process.on(signal, function() {
+        if (process.listeners(signal).length > Screen.total) {
+          return;
+        }
+        nextTick(function() {
+          process.exit(0);
+        });
+      });
+    });
+  }
+
+  process.on('exit', function() {
+    Screen.list.slice().forEach(function(screen) {
+      screen.destroy();
+    });
+  });
+};
+
 Screen.prototype.__proto__ = Node.prototype;
 
 Screen.prototype.type = 'screen';
@@ -284,6 +306,7 @@ Screen.prototype.postEnter = function() {
   var self = this;
   if (this.options.debug) {
     this.debugLog = new Log({
+      screen: this,
       parent: this,
       hidden: true,
       draggable: true,
@@ -326,6 +349,22 @@ Screen.prototype.postEnter = function() {
   }
 };
 
+Screen.prototype.destroy = function() {
+  this.leave();
+
+  var index = Screen.list.indexOf(this);
+  if (~index) {
+    Screen.list.splice(index, 1);
+    Screen.total--;
+    if (Screen.total === 0) {
+      Screen.global = null;
+    }
+    this.emit('destroy');
+  }
+
+  this.program.destroy();
+};
+
 Screen.prototype.log = function() {
   if (this.debugLog) {
     this.debugLog.log.apply(this.debugLog, arguments);