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Add Zotero.lazy() and use in _getConnectionAsync

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I tried to describe what this function does earlier today and failed.
Hopefully the code is clearer.
This commit is contained in:
Simon Kornblith 2013-08-14 21:36:50 -04:00
parent c95223724d
commit 857fcfa31d
2 changed files with 22 additions and 12 deletions
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15
chrome/content/zotero/xpcom/db.js
View file

@ -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));
});
/*

19
chrome/content/zotero/xpcom/zotero.js
View file

@ -1518,6 +1518,25 @@ Components.utils.import("resource://gre/modules/Services.jsm");
return;
};
/**
* 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.
*