[NTG-context] Simple rings with svg

[Aditya Mahajan]

On Thu, 10 May 2012, Hans Hagen wrote:

> On 10-5-2012 16:59, Aditya Mahajan wrote:
>> On Thu, 10 May 2012, Ian Lawrence wrote:
>> 
>>> I read on the wiki that now svg is natively supported. Hmm.
>> 
>> No. You need to have inkscape installed (and in your PATH) for svg to
>> pdf conversion to work.
>> 
>>> FWIW, I cannot find the intermediate file
>>> 'm_k_i_v_ChangingField_ILUC.pdf' on my disk either…both graphics files
>>> are in the same location, both exist, both are named correctly….
>> 
>> @Hans, could we change the conversion so that it checks for inkscape and
>> gives a more sensible warning if inkscape is absent?
>
> so what is a robust check ...

How about just implementing the unix which command in lua?

(untested code)

function which(string file)
   local path = os.getenv("PATH")
   local splitter = lpeg.splitat(io.fileseparator)
   local directories = lpeg.match(splitter, path)

   for dir in directories
     if io.exists(file.join(dir,file)) then
       return true
     end
   end

   return false
end