was Re: PIDL/IDL question(s) now RFC patch "support processing 'local' attribute"

[Jelmer Vernooij]

On Thu, Aug 21, 2014 at 11:25:55AM +0100, Noel Power wrote:
> On 07/08/14 15:36, Noel Power wrote:
> > On 09/05/14 12:32, Noel Power wrote:
> >> Hi,
> >>
> >> the following is a set of structures (simplified) expressed in c ( or
> >> more likely pseudo-c ) that I wish to marshall. Using PIDL would be
> >> ideal, I have tried but still I have some difficulty expressing the
> >> structures so they would be marshalled in the correct way. Note: I don't
> >> have control of the structures representation and cannot adjust them to
> >> suit what is possible in idl. Note: I am pretty pidl disabled also so
> >> any advice welcome
> >>
> >>   struct bounds {
> >>       uint16 nelems;
> >>       uint16 lbound;
> >>   };
> >>
> >>   struct ndim_arraytype {
> >>       uint16 ndims;
> >>       uint16 somefield;
> >>       struct bounds *bounds; /* bounds[ndims] */
> >>       string values; /* values[elems] - where elems is calculated by
> >> summing the nelems values from each bound struct stored above */
> >>   };
> >>
> >> PROBLEM A: Although I can see howto to represent the bounds array above
> >> (simple inline array) in idl I can't see how to do that for the elements
> >> array where the number of elements is determined at runtime from the
> >> contents of the bounds array. Aspirationally I would like to do
> >> something like
> >>
> >>   typedef [public] struct {
> >>       uint16 ndims;    
> >>       uint16 somefield;    
> >>       struct bounds bounds[ndims]
> >>       string values[custom_fn(bounds, ndims)];
> >>   } ndim_arraytype;
> >>
> >> and indeed the generated code looks like it would do what I require,
> >> however the custom_fn is obviously undefined and therefore wont build. I
> >> can I guess create a new source & header file that contains the custom
> >> function I need and build it with the generated ndr_xyz files, but is
> >> this the correct thing to do?, am I depending on some unintentional
> >> behaviour by using 'variant elements[custom_fn(bounds, ndims)];'? or
> >> indeed is there a better way to do this ?
> >
> Alternatively there is the 'local' attribute that MIDL accepts ( note: I
> am not a MIDL user but just was playing a little with it because the
> more I thought about it, the more it seemed there should be an option to
> do something similar to above) The following patches add *simple*
> support for processing the 'local' attribute
> 
> a) in the interface attribute list
> &
> b) in the function attribute list
> 
> Essentially the 'local' attribute generates a non-remote/local function
> prototype in the header file, more details in the commit message.

I'm not sure if I understand your use case here (for [local]). This will just
generate a function prototype as far as I can tell. What is that good for?

Cheers,

Jelmer