Am 25.01.2014 01:07, schrieb Hans Hagen:
> On 1/24/2014 7:41 PM, Peter Rolf wrote:
>> Am 24.01.2014 14:45, schrieb Hans Hagen:
>>> On 1/24/2014 1:35 PM, Peter Rolf wrote:
>>>> Hi,
>>>>
>>>> I try to create a Metapost path in lua and it works so far for the
>>>> attached example. But a call of that function from another lua function
>>>> sadly fails (no path visible after call). The code seems to be executed
>>>> later (the output from 'show pid;' appears somewhere later in the log).
>>>>
>>>> How can I ensure that the code is executed at runtime?
>>>
>>> I don't understand the issue but isn't there a
>>>
>>>      metafun("draw p;")
>>>
>>> missing then?
>>>
>> Setting the bounding box has the same effect, as drawing something.
>> Both methods avoid that the emtpy graphic is ignored by ConTeXt.
>>
>> Anyhow, the MP path is not available in metapost.variables after the
>> function call. If there is no other way I have to call the function from
>> the TeX side (like in the attached example). Will look into that
>> tomorrow.
> 
> %D We also provide an outputless run:
> 
> \unexpanded\def\startMPcalculation
>
I tried that command, but couldn't get it to work on the lua side.

The first pure MP line after context.startMPcalculation() raises a lua
error and a combination with metafun() is also not working. So how to
use this in lua?


Anyhow, the problem is the execution time of the MP graphic. I changed
the attached example a bit, so that you can see it.
The inspect() in drops.foo() gives an empty table, while the second
inspect on the TeX side shows the path "drops:foo".

I need the path right after the call (it needs to be adapted to IM
afterwards; mainly scaling and shifting). Is there a way to "force" the
execution of the graphic without switching back to the TeX side?


Peter