This new warning adds a lot of warnings in the Cappuccino frameworks. I have turned off
the warning in the Jakefiles when compiling most of the Cappuccino frameworks. But it is
on as default for any user projects.
So there is also a new feature to turn off/on warnings as a compiler flag.
These flags are (all flags are on as default):
-Wunused-but-set-variable Warning when a local variable is never read.
-Wshadow-ivar Warning when a local variable is shadowing an instance variable for the class.
-Wcreate-global-inside-function-or-method Warning when creating a global variable inside a function or method.
-Wunknown-class-or-global Warning when a class or global variable is not known.
-Wunknown-ivar-type Warning when the type for an instance variable is not known.
To turn off a flag add a 'no-' prefix. Example: -Wno-unused-but-set-variable
For an example how to use it in a Jakefile please look at the Jakefiles in this commit.
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;
...
The life will be easier to have the same in both environments.
Warnings and errors now don’t use read only properties for line and column information. So the test cases in Toolstest.j now work in modern JS engines.
It is also easier to set options for the compiler.
Earlier the compiler generated the 'if' without the last ';' when a empty statement is used, with sometimes devastating result. The same if an empty statement was after the 'else'.
I have also added a test case for some different empty statement senarios.
The Objective-J parser and compiler now handles protocol syntax. The Objective-J runtime has new functions to handle protocols. The method 'conformsToProtocol:' has been added to CPObject as an instance and a class method.
The program below crashed on the last line with a 'null is not an object' error message. Also added a test case.
@implementation MyObject {
- (int):(int)a {
return a;
}
@end
var a = [[MyObject alloc] init];
var b = [a:3];
With the new compiler, messages such as `[a in:b]` could not be sent, the "in:" parameter throwing an unexpected token error. This was true both if "in" was the first argument or any of the subsequent parameters (such as in `[a something:X in:Y]`).
Alfred Wärnsäter
Martin Carlberg
Antoine Mercadal
Martin Carlberg
Alexander Ljungberg
Blair Duncan
Alexander Ljungberg
Paul Baumgart
Francisco Ryan Tolmasky I