www

commit d5439363070f5f0f48b02fc778a591ac65955d3e
parent c95223724dd1d9d417aed7cf032bd27b90ae4100
Author: Dan Stillman <dstillman@gmail.com>
Date:   Wed, 14 Aug 2013 22:00:32 -0700

Merge pull request #374 from simonster/lazy

Add Zotero.lazy() and use in _getConnectionAsync
Diffstat:
M
chrome/content/zotero/xpcom/db.js
 | 
15
+++------------
M
chrome/content/zotero/xpcom/zotero.js
 | 
19
+++++++++++++++++++

2 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/chrome/content/zotero/xpcom/db.js b/chrome/content/zotero/xpcom/db.js
@@ -70,7 +70,6 @@ Zotero.DBConnection = function(dbName) {
 	this._dbName = dbName;
 	this._shutdown = false;
 	this._connection = null;
-	this._connectionAsync = null;
 	this._transactionDate = null;
 	this._lastTransactionDate = null;
 	this._transactionRollback = false;
@@ -1021,23 +1020,15 @@ Zotero.DBConnection.prototype.asyncResult = function (val) {
 /**
  * Asynchronously return a connection object for the current DB
  */
-Zotero.DBConnection.prototype._getConnectionAsync = function () {
-	if (this._connectionAsync) {
-		return Q(this._connectionAsync);
-	}
-	
+Zotero.DBConnection.prototype._getConnectionAsync = Zotero.lazy(function() {
 	var db = this._getDBConnection();
 	var options = {
 		path: db.databaseFile.path
 	};
 	var self = this;
 	Zotero.debug("Asynchronously opening DB connection");
-	return Q(this.Sqlite.openConnection(options)
-	.then(function(conn) {
-		self._connectionAsync = conn;
-		return conn;
-	}));
-};
+	return Q(this.Sqlite.openConnection(options));
+});
 
 
 /*
diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
@@ -1519,6 +1519,25 @@ Components.utils.import("resource://gre/modules/Services.jsm");
 	};
 	
 	/**
+	 * Generate a function that produces a static output
+	 *
+	 * Zotero.lazy(fn) returns a function. The first time this function
+	 * is called, it calls fn() and returns its output. Subsequent
+	 * calls return the same output as the first without calling fn()
+	 * again.
+	 */
+	this.lazy = function(fn) {
+		var x, called = false;
+		return function() {
+			if(!called) {
+				x = fn.apply(this);
+				called = true;
+			}
+			return x;
+		};
+	};
+	
+	/**
 	 * Pumps a generator until it yields false. See itemTreeView.js for an example.
 	 *
 	 * If errorHandler is specified, exceptions in the generator will be caught