• Rick Mann (13/13) Jan 31 2007 I have an external variable declared like this:
• Bradley Smith (17/33) Jan 31 2007 Why doesn't private protection work on structs? I tested it with DMD
• Bill Baxter (4/42) Jan 31 2007 Isn't that because protection attributes are applied at the module
• Bradley Smith (6/31) Jan 31 2007 That's exactly it. Thanks. I forgot that fact. If I move main() into
• Derek Parnell (22/23) Jan 31 2007 The 'private' protection means that such items cannot be accessed by thi...

Rick Mann <rmann-d-lang latencyzero.com> writes:

I have an external variable declared like this:

struct
ControlID
{
	uint			signature;
	int				id;
};
extern extern (C) const HIViewID kHIViewWindowContentID;

But when I am able to write code like this without complaint from the compiler
(GDC 0.21/DMD 1.00):

kHIViewWindowContentID.signature = 123;

I'd like to prevent that. Is such a thing possible?

TIA,
Rick

Bradley Smith <digitalmars-com baysmith.com> writes:

Rick Mann wrote:
 I have an external variable declared like this:
 
 struct
 ControlID
 {
 	uint			signature;
 	int				id;
 };
 extern extern (C) const HIViewID kHIViewWindowContentID;
 
 But when I am able to write code like this without complaint from the compiler
(GDC 0.21/DMD 1.00):
 
 kHIViewWindowContentID.signature = 123;
 
 I'd like to prevent that. Is such a thing possible?
 

Why doesn't private protection work on structs? I tested it with DMD 
1.003 and was surprised by the result.

struct ControlID {
   private uint signature_;
   private int id_;
	
   uint signature() {
     return signature_;
   }
}

void main() {
   ControlID id;
   id.signature = 123;  // Compiler error
   uint i = id.signature;

   id.signature_ = 123;  // Doesn't fail. Should it?
}

Bill Baxter <dnewsgroup billbaxter.com> writes:

Bradley Smith wrote:
 Rick Mann wrote:
 I have an external variable declared like this:

 struct
 ControlID
 {
     uint            signature;
     int                id;
 };
 extern extern (C) const HIViewID kHIViewWindowContentID;

 But when I am able to write code like this without complaint from the 
 compiler (GDC 0.21/DMD 1.00):

 kHIViewWindowContentID.signature = 123;

 I'd like to prevent that. Is such a thing possible?

 
 Why doesn't private protection work on structs? I tested it with DMD 
 1.003 and was surprised by the result.
 
 struct ControlID {
   private uint signature_;
   private int id_;
     
   uint signature() {
     return signature_;
   }
 }
 
 void main() {
   ControlID id;
   id.signature = 123;  // Compiler error
   uint i = id.signature;
 
   id.signature_ = 123;  // Doesn't fail. Should it?
 }

Isn't that because protection attributes are applied at the module 
level, not class/struct level?

--bb

Bradley Smith <digitalmars-com baysmith.com> writes:

Bill Baxter wrote:
 Bradley Smith wrote:
 Why doesn't private protection work on structs? I tested it with DMD 
 1.003 and was surprised by the result.

 struct ControlID {
   private uint signature_;
   private int id_;
       uint signature() {
     return signature_;
   }
 }

 void main() {
   ControlID id;
   id.signature = 123;  // Compiler error
   uint i = id.signature;

   id.signature_ = 123;  // Doesn't fail. Should it?
 }

 
 Isn't that because protection attributes are applied at the module 
 level, not class/struct level?
 
 --bb

That's exactly it. Thanks. I forgot that fact. If I move main() into 
another module, I get the error "struct privateStruct.ControlID member 
signature_ is not accessible".

Thanks,
   Bradley

Derek Parnell <derek nomail.afraid.org> writes:

On Wed, 31 Jan 2007 15:33:24 -0800, Bradley Smith wrote:

 Why doesn't private protection work on structs? 

The 'private' protection means that such items cannot be accessed by things
in other *modules* and not just other classes/structs. In other words, any
thing in a module has access to everything in the same module.

However, a long-existing bug means that you can still subvert this
protection by simply referencing a private item in a different module by
using it's fully qualified name.

 -------
 module foo;
 private int A;

 -------
 module bar;
 import foo;
 . . .
    foo.A = 42;  // Allowed but should not be.
    A = 42;      // Correctly disallowed.

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocrity!"
1/02/2007 11:17:14 AM