Proposal: .isizeof property for compile-time instance size

[S. Chancellor]

On 2006-04-09 13:28:41 -0700, Sean Kelly <sean at f4.ca> said:

> (this was originally posted to D bugs, but turned out to be a mistake 
> so I'm reposting it here for discussion)
> 
> As D lacks a lexical specifier for class reference types there is 
> currently no way to determine the size of a class instance at 
> compile-time.  A simple solution would be to add a new property, valid 
> for pointer and reference types, that evaluates to the size of the 
> referenced type.  Thus:
> 
> (byte*).isizeof == byte.sizeof == 1
> (byte**).isizeof == (byte*).sizeof == 4 (on 32-bit systems)
> byte.isizeof == Error: property isizeof is only valid for reference types.
> 
> MyClass { int x, y; }
> MyClass.isizeof == 8
> (MyClass*).isizeof == MyClass.sizeof == 4 (on 32-bit systems)
> 
> Multiple levels of indirection can be eliminated using recursive 
> templates, so there is no reason to collapse multiple levels of 
> indirection and return the size of the final referenced type.

I'd rather see my proposal implemented, and then classes be in terms of 
true references and then ad a "psizeof" to get the size of the physical 
pointer or stack variable.  Of course, I would be bias toward my 
proposal. :)

-S.