Gosu Basics for Null

[chiasso...@gmail.com]

Hello.  in Gosu, is Null a legal value for any variable?

[Alan Keefer]

Gosu works like Java in this respect:  null is a legal value for any Object type, but not for primitive types.

-Alan

On Tue, Mar 10, 2015 at 7:01 AM, <chiasso...@gmail.com> wrote:

Hello.  in Gosu, is Null a legal value for any variable?

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[Wojciech Sadlik]

Not quite Alan. It's unlike in Java. Look for example:

var a : int = null
print("Null value equals: " + a)
var sum : int = a + 3
print("Null + 3 equals: " + sum)

Null value equals: 0

Null + 3 equals: 3

So as you can see it's possible to assign null to primitives and in this case convert it to zero.

[Alan Keefer]

What version of Gosu are you using there?  Null was a legal value for primitives in Gosu in much older versions, back when Gosu was executed off of the parsed AST rather than compiled down into Java bytecode.  Once we moved to Java bytecode (probably 5 years ago?), we had to tighten things up to obey the Java semantics, so null is no longer a valid value for an int in Gosu.

-Alan

[Luca Boasso]

Yep, that code is illegal in the current version of Gosu.