Nullablity

P T Withington ptw at pobox.com
Sat Jun 24 06:33:34 PDT 2006


On 2006-06-23, at 13:14 EDT, Jeff Dyer wrote:

> Clearly a proposal that allows AS3 code that is free
> of null pointer errors to compile and run unchanged would be much
> preferred to proposals that don't.

Since I'm jumping in to the middle of this process, let me summarize  
my understanding.  Tell me if I'm wrong:

The proposal on the table is to make all types _not_ nullable by  
default.  If a program has no null pointer errors, that should not  
affect the program.  There is an implementation detail for compiler  
writers that it is _not_ an error to have an uninitialized variable  
so long as it is always initialized to a type-correct value before it  
is read (requires flow analysis in the compiler).  It would be easier  
for the compiler implementor to not permit that case in the language,  
but I don't think that is being proposed -- such a change _would_  
break correct programs.



More information about the Es4-discuss mailing list