struct vs class for a simple token in my d lexer

[Roman D. Boiko]

On Monday, 14 May 2012 at 16:41:39 UTC, Jonathan M Davis wrote:
> On Monday, May 14, 2012 17:10:23 Roman D. Boiko wrote:
>> (Subj.) I'm in doubt which to choose for my case, but this is a
>> generic question.
>> 
>> http://forum.dlang.org/post/odcrgqxoldrktdtarskf@forum.dlang.org
>> 
>> Cross-posting here. I would appreciate any feedback. (Whether 
>> to
>> reply in this or that thread is up to you.) Thanks
>
> For the question in general, there are primarily 2 questions to 
> consider:
>
> 1. Do you need inheritance/polymorphism?
> don't have inheritance.
>
> 2. Do you need a value type or a reference type?
>
> If you need inheritance/polymorphism, you have to use classes, 
> because structs
>
> If you want a value type, you have to use structs, because 
> classes are
> reference types.
>
> If you want a reference type, then you can use either a class 
> or a struct, but
> it's easier with classes, because classes are always reference 
> types, whereas
> structs are naturally value types, so it can take more work to 
> make them
> reference types depending on what its member variables are.
>
> One other thing to consider is deterministic destruction. The 
> only way to get
> deterministic destruction is to have a struct on the stack. 
> Value types will
> naturally get that, but if you want a reference type with 
> determinstic
> destruction, then you're probably going to have to use a 
> ref-counted struct.
>
> In the vast majority of cases, that should be enough to decide 
> whether you
> need a class or a struct. The main case that it doesn't is the 
> case where you
> want a reference type and don't necessarily want a class, and 
> that decision
> can get complicated.
>
> In the case of a token in a lexer, I would definitely expect 
> that to be a value
> type, which means using a struct.
>
> - Jonathan M Davis
Semantics is clearly of value type. But it would be nice to
minimize size of instance to be copied. (I could simply split it
into two, if some part is not used in most scenarios.)

Just curious: how to implement a struct as ref type? I could add
indirection (but then why not just use a class?), or simply pass
by ref into all methods. Are there any other options?

Thanks to everybody for your feedback, it looks like I'll stay
with struct.