Getting InputStream errors when including a call to ElementData within an Import definition

So I am writing an ImportExport converter for a common chemistry file format, and I've run up against a problem that seems to be about shared streams and whatnot. I followed the directions on this page.

To work the example, create a random text file whose contents do not matter.

Export["testfile.txt", "hello"];


The definition for the Import converter is as follows

ImportExportRegisterImport["TestFormat", TestFormatTestFormatImport];
TestFormatTestFormatImport[filename_String, options___] :=
Module[{temp},
(*Do some stuff, all works just fine*)
temp = ElementData["C", "AtomicNumber"];
{"Test" -> temp}];


All this does is call for the atomic number associated with the symbol C. If you test it out it seems to work just fine:

In[3]:= Import["testfile.txt",{"TestFormat","Test"}]
Out[3]= 6


But any subsequent call to ElementData gives a stream error:

In[4]:= ElementData["F","AtomicNumber"]
During evaluation of In[4]:= General::openx: InputStream[C:\Users\myusername\AppData\Roaming\Mathematica\Paclets\Repository\ElementData-7.0.28\Data\ElementData.wdx,122] is not open. >>
Out[4]= \$Failed


But, if I make a call to ElementData before I make the Import command, then the errors go away.

In[1]:= ImportExportRegisterImport["TestFormat",
TestFormatTestFormatImport];
TestFormatTestFormatImport[filename_String, options___] :=
Module[{temp},
(*Do some stuff, all works just fine*)
temp = ElementData["C", "AtomicNumber"];
{"Test" -> temp}];
ElementData["H", "AtomicNumber"]
Import["testfile.txt", {"TestFormat", "Test"}]
ElementData["F", "AtomicNumber"]

Out[3]= 1

Out[4]= 6

Out[5]= 9


This is all well and good, but I don't want to have to randomly make a call to ElementData before I do an Import command every time.

What is going on here and how can I fix it?

Thanks

• I am curious, did you make any progress? I am just facing a very similar problem, with CountryData and webMathematica... – Pinguin Dirk Oct 10 '13 at 8:13
• I just asked a "similar" question, see mathematica.stackexchange.com/questions/33783/…. Probably close to dupe, but hopefully this will bring us closer to the solution – Pinguin Dirk Oct 10 '13 at 9:06
• No progress on this yet. I heard from someone else that wasn't able to reproduce my error. So I need to try it on my home PC to see if it is just a problem with my local installation or if it's more general. – Jason B. Oct 10 '13 at 16:11