[Xcb] sizeof paramters for length less lists

[Peter Harris]

On 2015-02-26 01:58, chris at demorecorder.com wrote:
> P.S.: @all: Here's some context, so people on this list can understand what's this about:
> 
> In current XCB, the length of the rectangles list of request SetPictureClipRectangles
> is not specified in render.xml:
>   <request name="SetPictureClipRectangles" opcode="6">
>     <field type="PICTURE" name="picture" />
>     <field type="INT16" name="clip_x_origin" />
>     <field type="INT16" name="clip_y_origin" />
>     <list type="RECTANGLE" name="rectangles" />
>   </request>
> 
> This needs to be fixed for some applications, including server-side XCB.
> So, the xml will be changed as follows, by using the length-field of the
> request to compute the length of the rectangles-list:
> 
>   <request name="SetPictureClipRectangles" opcode="6">
>     <field type="PICTURE" name="picture" />
>     <field type="INT16" name="clip_x_origin" />
>     <field type="INT16" name="clip_y_origin" />
>     <list type="RECTANGLE" name="rectangles" >
> 	<op op="/">
>             <op op="-">
>                 <fieldref>length</fieldref>
>                 <value>3</value>
>     	    </op>
>             <value>2</value>
>         </op>
>     </list>
>   </request>

I'm confused. Earlier you said "so, don't use "(length - 3)/2" inside,
but use rectangles_len", and then you went to a lot of manual effort to
define rectangles_len as "(length - 3)/2".

Given that rectangles_len is already implied by a list with no length,
and given that creating all the <op>s by hand is error prone, I'd rather
leave the XML as-is.

If the generator needs this <op> block for something, shouldn't it be
calculated from the rest of the request and inserted by an earlier pass
in the generator? Or did I miss something?

Peter Harris
-- 
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