Definitive list of storage classes

[Jonathan M Davis]

On Sunday, April 15, 2012 01:49:09 Daniel Murphy wrote:
> "Jonathan M Davis" <jmdavisProg at gmx.com> wrote in message
> news:mailman.1707.1334377994.4860.digitalmars-d at puremagic.com...
> 
> > I'd like to know which modifiers are considered to be storage classes. The
> > term
> > seems to be used on a lot more than actually qualifies (including using
> > the
> > term for the type qualfiers: const, immutable, and shared), and even the
> > documentation uses it on stuff that I wouldn't have thought would be
> > considered
> > storage classes, because they have no effect on how variables are stored
> > or
> > linked (e.g. synchronized).
> > 
> > Someone asked about it on stackoverflow, and my explanation is not as good
> > as
> > it should be simply because I can't find a definitive list anywhere:
> > 
> > http://stackoverflow.com/questions/10150510/what-are-the-storage-classes-i
> > n-d
> > 
> > - Jonathan M Davis
> 
> There's always the list in 'declaration.h'.

That's clearly not the list, since it includes const, immutable, and shared, 
which are type qualifiers rather than storage classes. It also has stuff like 
init in it, which isn't even vaguely a storage class. All of the storage 
classes may be in that list, but I don't know how you'd figure out which ones 
they are from that list.

> If I had to guess I'd say 'storage class' meant something much more specific
> in C than it does in D, where it seems to mean properties of a declaration
> that do not affect the type.

Except that both Walter and Andrei seem to talk about type 
qualifiers/constructors and storage classes as if they meant essentially the 
same thing as in C/C++. For instance, talking about const as being a type 
qualifier rather than a storage class doesn't mean anything to a non-D audience 
unless it means essentially the same thing as in C. Also, the documentation 
lists synchronized as being a storage class whereas it affects no variables 
whatsoever and all of the descriptions of storage classes in TDPL act like 
storage classes are for variables only. But synchronized doesn't affect 
scoping, storage, or linking at all as a storage class in C would, so that 
would at least seem to indicate that something other than the C definition is 
being used.

Regardless, if a storage class does not have a specific definition separate from 
D which can be applied to D, then D needs to give its own definition for what 
on earth the term means, and I don't find _anywhere_ that does that. Everywhere 
that mentions it seems to assume that you have some idea of what it means 
already. TDPL _does_ sort of try and define it, but not really. It pretty much 
just lists certain modifiers as being storage classes without giving a full 
list or explaining exactly what constitutes a storage class. The closest thing 
that it gives to a definition

"Each function parameter (base and exponent in the example above) has, in 
addition to its type, an optional storage class that decides the way that 
arguments are passed to the function when invoked."

would seem indicate that static (which it later says is a storage class) isn't 
a storage class at all, since storage classes would only apply to function 
parameters (which would also disqualify synchronized as a storage class, which 
would be at odds with the online docs).

So, I'd like an official definition of storage class with a list of what qualifies 
as a one in D. But it wouldn't surprise me at all if Walter's the only one who 
can do that.

- Jonathan M Davis