Martin Carlberg
81c02f24c6
The msgSend function has always returned nil if the receiver has been nil or undefined. Example: var a = undefined; var b = [a someSelector]; // b = nil The variable b is now nil. This pull request adds the ability for the msgSend function to return undefined if the receiver is undefined. If the receiver is nil it still return nil. The above example again: var a = undefined; var b = [a someSelector]; // b = undefined The variable b is now undefined. Background. The use of nil in Objective-C corresponds to the use of null in C and C++ and stands for "no value". A fundamental function in Objective-C is when you send a message to a receiver that is nil the result is again a nil value. This can be very convenient as you don't need the check if a receiver is nil before sending a message to it. Objective-J adds the ability the use class structures and message send functionality for Javascript in the same way as Objective-C adds this to C and C++. Javascript also has the value null and is handled in the same way for Objective-J. Javascript also has the value undefined that stands for "not yet defined". This can sometimes be confusing and many try to handle null and undefined as the same thing. This is almost what Objective-J and the Cappuccino frameworks always has been doing. They try to always check for both null and ``undefined and always return nil but never undefined. We can say that Objective-J understands undefined but will try to translate it to nil. Why do we need this change. Javascript has both null and undefined and Objective-J is a superset of Javascript. It is now very hard to use undefined in Objective-J code as it will always try to translate it to nil. There are some Javascript libraries that use both null and undefined values and they are very hard to use from Objective-J programs today. Same if you decide to use nil and undefined as a value in your own Objective-J code. This small change will make undefined a full member of the Objective-J language. It should be as it is a superset of Javascript. The Cappuccino frameworks will still handle undefined but only return nil. How will it impact. Today most methods will never return undefined so this is a very limited problem. If any does this the main concern is if some code will only check for nil and not undefined. Example: var a = [someObject someSelector]; If (a === nil) a = 42; ... If the variable someObject contains undefined the variable a will now be set to undefined instead of nil. But the variable a will then never be set to 42. The correct way is to check for both nil and undefined like this: var a = [someObject someSelector]; If (a == nil) a = 42; ...
Welcome to Cappuccino!
Introduction
Cappuccino is an open source framework that makes it easy to build desktop-caliber applications that run in a web browser.
With Cappuccino, you don't concern yourself with HTML, CSS, or the DOM. You write applications with the APIs from Apple's Cocoa frameworks and the Objective-J language.
Check out a live demo of the widgets in Cappuccino
Check out some live demos and tutorials
For more information, see the
Follow @cappuccino on Twitter for updates on the project.
If you discover any bugs, please file a ticket.
System Requirements
To run Cappuccino applications, all you need is a HTML5 compliant web browser.
Our tight integration with Xcode on MacOS brings the full power of visual Cocoa development to the web.
However, you can also work on other platforms using only a simple text editor.
Getting Started
To write you first application, download the starter package.
To contribute to Cappuccino, please read here: Getting and Building the Source.
License
This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA