commit 857fcfa31dd5d69da533217a5bfd4a702b2b5a2b
parent c95223724dd1d9d417aed7cf032bd27b90ae4100
Author: Simon Kornblith <simon@simonster.com>
Date: Wed, 14 Aug 2013 21:36:50 -0400
Add Zotero.lazy() and use in _getConnectionAsync
I tried to describe what this function does earlier today and failed.
Hopefully the code is clearer.
Diffstat:
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
