[M3devel] Referencing opaque C structs in M3 code?

[Tony Hosking]

You can have a

TYPE foo = BRANDED "foo" ADDRESS

to distinguish from other void types.

On 5 Mar 2010, at 16:03, hendrik at topoi.pooq.com wrote:

> On Thu, Mar 04, 2010 at 04:59:42PM -0500, Tony Hosking wrote:
>> You can assume that ADDRESS is entirely interchangeable with a C void *.
> 
> What struct opaque_foo_t provides that void doesn't is some further 
> type-checking -- struct opaque_foo_t is a different type from struct 
> other_foo_t.
> 
> Presumably you should use Modula 3 techniques for making an opaque 
> types in your interface.
> 
> - hendrik
> 
>> 
>> Antony Hosking | Associate Professor | Computer Science | Purdue University
>> 305 N. University Street | West Lafayette | IN 47907 | USA
>> Office +1 765 494 6001 | Mobile +1 765 427 5484
>> 
>> 
>> 
>> 
>> On 4 Mar 2010, at 16:29, Chris wrote:
>> 
>>> Alright, this has thrown me for a bit of a loop...no pun intended...
>>> 
>>> Suppose I'm linking my Modula 3 code with a C library where the public API has a declaration like this...
>>> 
>>> typedef struct opaque_foo_t opaque_foo_t;
>>> 
>>> And the type opaque_foo_t is defined in the private part of the library.
>>> 
>>> Do I need to create a seperate representation of the structure for my Modula3 program or can I just create a pointer for it and pass the pointer around? Assuming of course I dont have to actually reference anything inside opaque_foo_t.  Would I just create an UNTRACED REF Ctypes.void_star or something similiar?
>>> 
>>> I'm a little puzzled. Any help would be appreciated.
>>> 
>>> 
>>> 
>>> -- 
>>> Chris <Highjinks at gmx.com>
>>