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JavaScript Preferences Class

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This class encapsulates many of the commonly used features of Mozilla's preferences-related interfaces into a centralized, reusable class. It traps exceptions, allows you to specify default values for preferences when they don't exist in any preference tree, and keeps code organized by localizing preference manipulation to a single class. The only interfaces not yet supported are nsILocalFile and nsIRelativeFilePref. Feel free to add them if you like. Sample usage is shown in the leading comments. This class encapsulates many of the commonly used features of Mozilla's preferences-related interfaces into a centralized, reusable class. It traps exceptions, allows you to specify default values for preferences when they don't exist in any preference tree, and keeps code organized by localizing preference manipulation to a single class. The only interfaces not yet supported are nsILocalFile and nsIRelativeFilePref. Feel free to add them if you like. Sample usage is shown in the leading comments.
-<pre>+<pre>Code temporarily taken down for maintanence</pre>
-/**************************************************************************+
- * preferences.js - a javascript class which provides a safe wrapper *+
- * around nsIPrefService. *+
- * *+
- * It keeps code clean by centralizing the use of *+
- * nsIPrefService, translating exceptions into null or *+
- * false return values (as appropriate), typechecking *+
- * all values, and other good things. *+
- * *+
- * author: eric h. jung (grimholtz@yahoo.com) *+
- * version: 0.1 *+
- * date: 07 March 2005 *+
- * *+
- * Usage: Include this file in your code then -- *+
- * *+
- * var prefs = new PrefsWrapper("extensions.myextension."); *+
- * prefs.setXXX("foo.bar", fooBarPref); *+
- * // Note you can optionally provide a default value for all *+
- * // getters. If the pref doesn't exist in either the current or *+
- * // default preference tree, the default value will be *+
- * // returned. *+
- * var fooBarPref = prefs.getXXX("foo.bar"); *+
- * var fooBarBarPref = prefs.getXXX("foo.bar.bar", "my default"); *+
- * *+
- * Read the comments of each function to see what it returns and when. *+
- * For details about Mozilla preferences, see *+
- * http://kb.mozillazine.org/Dev_:_Using_preferences *+
- * *+
- **************************************************************************/+
- +
- +
-/**+
- * Constructor+
- */+
-function PrefsWrapper(branch) {+
- this._prefsService = this._prefsService.getBranch(branch);+
-}+
- +
-/**+
- * Retrieves the state of an individual boolean preference.+
- * Returns true/false if the preference exists in either the current or +
- * default preference tree. Returns the default argument+
- * if the preference does not exist in either of those trees, or is not of boolean type.+
- * If no default argument is specified, null is returned in its place.+
- */+
-function getBool(prefName, defawlt) {+
- try {+
- return this._prefsService.getPrefType(prefName) == this._prefsService.PREF_BOOL ?+
- this._prefsService.getBoolPref(prefName) : defawlt;+
- }+
- catch (e) {+
- return defawlt;+
- }+
-}+
- +
-/**+
- * Retrieves the state of an individual string preference.+
- * Returns the value of the preference if it exists in either the current or+
- * default preference tree. Returns the default argument+
- * if the preference does not exist in either of those trees, or is not of string type.+
- * If no default argument is specified, null is returned in its place.+
- */+
-function getChar(prefName, defawlt) {+
- try {+
- return this._prefsService.getPrefType(prefName) == this._prefsService.PREF_STRING ?+
- this._prefsService.getCharPref(prefName) : defawlt;+
- }+
- catch (e) {+
- return defawlt;+
- }+
-}+
- +
-/**+
- * Retrieves the state of an individual integer preference.+
- * Returns the value of the preferenceif it exists in either the current or+
- * default preference tree. Returns the default argument+
- * if the preference does not exist in either of those trees, or is not of integer type.+
- * If no default argument is specified, null is returned in its place.+
- */+
-function getInt(prefName, defawlt) {+
- try {+
- return this._prefsService.getPrefType(prefName) == this._prefsService.PREF_INT ?+
- this._prefsService.getIntPref(prefName) : defawlt;+
- }+
- catch (e) {+
- return defawlt;+
- }+
-}+
- +
-/**+
- * Retrieves the state of an individual Unicode string preference.+
- * Returns the value of the preference if it exists in either the current or+
- * default preference tree. Returns the default argument+
- * if the preference does not exist in either of those trees, or is not of string type.+
- * If no default argument is specified, null is returned in its place.+
- */+
-function getUnicodeChar(prefName, defawlt) {+
- try {+
- return this._prefsService.getPrefType(prefName) == this._prefsService.PREF_STRING ?+
- this._prefsService.getComplexValue(Components.interfaces.nsISupportsString).data : defawlt;+
- }+
- catch (e) {+
- return defawlt;+
- }+
-}+
- +
-/**+
- * Retrieves the state of an individual localized string preference.+
- * Returns the value of the preference if it exists in either the current or+
- * default preference tree. Returns the default argument+
- * if the preference does not exist in either of those trees, or is not of string type.+
- * If no default argument is specified, null is returned in its place.+
- */+
-function getLocalizedChar(prefName, defawlt) {+
- try {+
- return this._prefsService.getPrefType(prefName) == this._prefsService.PREF_STRING ?+
- this._prefsService.getComplexValue(Components.interfaces.nsIPrefLocalizedString).data : defawlt;+
- }+
- catch (e) {+
- return defawlt;+
- }+
-}+
- +
-/**+
- * Set the state of an individual boolean preference.+
- * Returns true if the value was successfully set; false if it wasn't set.+
- * _b_ can be a boolean, or case-insensensitive versions of+
- * "yes", "no", "true", or "false".+
- */+
-function setBool(prefName, b) {+
- if (typeof(b) == "boolean") {+
- this._prefsService.setBoolPref(prefName, b);+
- return true;+
- }+
- else {+
- try {+
- b = b.toLowerCase();+
- this._prefsService.setBoolPref(prefName, ("true" == b || "yes" == b));+
- return true;+
- }+
- catch (e) {+
- // toLowerCase() doesn't work and+
- // b isn't type boolean+
- return false;+
- }+
- }+
-}+
- +
-/**+
- * Set the state of an individual string preference.+
- * Returns true if the value was successfully set; false if it wasn't set.+
- */+
-function setChar(prefName, str) {+
- if (typeof(str) == "string") {+
- this._prefsService.setCharPref(prefName, str);+
- return true;+
- }+
- return false;+
-}+
- +
-/**+
- * Set the state of an individual integer preference.+
- * Returns true if the value was successfully set; false if it wasn't set.+
- */+
-function setInt(prefName, i) {+
- if (!isNaN(i) && String(i).indexOf(".") == -1) {+
- this._prefsService.setIntPref(prefName, i);+
- return true;+
- }+
- return false;+
-}+
- +
-/**+
- * Set the state of an individual Unicode string preference.+
- * Returns true if the value was successfully set; false if it wasn't set.+
- * The second argument, value, is a string which can contain non-ascii characters.+
- */+
-function setUnicodeChar(prefName, value) {+
- try {+
- var str = Components.classes["@mozilla.org/supports-string;1"].createInstance(Components.interfaces.nsISupportsString);+
- str.data = value;+
- this._prefsService.setComplexValue(prefName, Components.interfaces.nsISupportsString, str);+
- return true;+
- }+
- catch (e) {+
- return false;+
- }+
-}+
- +
-PrefsWrapper.prototype._prefsService =+
- Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefService);+
-PrefsWrapper.prototype.setInt = setInt;+
-PrefsWrapper.prototype.setChar = setChar;+
-PrefsWrapper.prototype.setBool = setBool;+
-PrefsWrapper.prototype.setUnicodeChar = setUnicodeChar;+
-PrefsWrapper.prototype.getInt = getInt;+
-PrefsWrapper.prototype.getChar = getChar;+
-PrefsWrapper.prototype.getBool = getBool;+
-PrefsWrapper.prototype.getUnicodeChar = getUnicodeChar;+
-PrefsWrapper.prototype.getLocalizedChar = getLocalizedChar;+
-</pre>+

Revision as of 20:06, 9 March 2005

Javascript Preferences Class

This class encapsulates many of the commonly used features of Mozilla's preferences-related interfaces into a centralized, reusable class. It traps exceptions, allows you to specify default values for preferences when they don't exist in any preference tree, and keeps code organized by localizing preference manipulation to a single class. The only interfaces not yet supported are nsILocalFile and nsIRelativeFilePref. Feel free to add them if you like. Sample usage is shown in the leading comments.

Code temporarily taken down for maintanence