Looking for champion - std.lang.d.lex

[Walter Bright]

Nick Sabalausky wrote:
> "Walter Bright" <newshound2 at digitalmars.com> wrote in message 
> news:i9qd8q$1ls4$1 at digitalmars.com...
>> 4. the tokens should be a value type, not a reference type
> 
> I'm curious, is your reason for this purely to avoid allocations during 
> lexing, or are there other reasons too?

It's one big giant reason. Storage allocation gets unbelievably costly in a 
lexer. Another is it makes tokens easy to copy. Another one is that classes are 
for polymorphic behavior. What kind of polymorphic behavior would one want with 
tokens?


> If it's mainly to avoid allocations during lexing then, maybe I've 
> understood wrong, but isn't D2 getting the ability to construct class 
> objects in-place into pre-allocated memory?

If you do that, might as well make them value types. The only reason classes 
exist is to support runtime polymorphism.


C++ made a vast mistake in failing to distinguish between value types and 
reference types. Java made a related mistake by failing to acknowledge that 
value types have any useful purpose at all (unless they are built-in).