Qs about structs and their references WRT C functions and variables

[torhu]

Rick Mann wrote:
> c) I need to declare a couple of extern structs. Can I just slap an "extern (C)" on these and all will be well? The spec seems to indicate that this is so, and it may be fine; I'm just looking for verification. e.g.:
> 
> struct
> ControlID
> {
> 	uint		signature;
> 	int		id;
> };
> typedef ControlID                       HIViewID;
> extern (C)
> const HIViewID kHIViewWindowContentID;

Try this:

extern extern (C) const HIViewID kHIViewWindowContentID;

http://www.digitalmars.com/d/declaration.html#extern

You need to add 'extern', just like in C headers.  Then 
kHIViewWindowContentID will be a pure declaration, and the linker will 
look elsewhere for a definition.  'extern (C)' by itself only causes the 
compiler to output the symbol with C instead of D name mangling.

If you link dynamically with the C lib, you are supposed to to add 
'export' too, even if it works without that in some cases.