Non-nullable references, again

Daniel Keep daniel.keep.lists at
Wed Dec 31 23:00:17 PST 2008

Michel Fortin wrote:
> On 2008-12-31 21:50:53 -0500, Daniel Keep <daniel.keep.lists at> 
> said:
>> Disclaimer: I'm not an expert on compilers.  Plus, I just got up.  :P
>> The key is that the parser has to know what "MyClass" means before it 
>> can figure out what the "?" is for; that's why it's context-dependant. 
>> D avoids this dependency between compilation stages, because it 
>> complicates the compiler.  When the parser sees "MyClass", it *doesn't 
>> know* that it's a type, so it can't distinguish between a nullable 
>> type and an invalid ?: expression.
> As far as I know, this can't be done with pointer declarations. Read this:
>     a * b;
> Is it a multiplication or a declaration of a pointer to type "a"? You 
> don't know until you resolve the identifiers. It's the exact same 
> situation for using "?" to denote nullable.
>> At least, I think that's how it works; someone feel free to correct me 
>> if it's not.  :P
> I belived the same for some time too, then found the above rebutal.

I don't think so; I believe that unary vs. binary operators are 
unambiguous.  "a * b" is "a multiply b" because it's "(expr) * (expr)". 
  It's pointer dereference when it's "* (expr)".

I keep in mind is that "(expr) < (expr) >" is ambiguous, but "* (expr)" 

Like I said, I'm not an expert, so take what I say with a grain of salt.

   -- Daniel

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