WeBWorK Problems

loops in NPL

loops in NPL

by Hal Sadofsky -
Number of replies: 2

We have a new server we are about to start using.  I believe we have the most recent version of the NPL (though maybe I'm supposed to call it the OPL now - I'm a bit confused about whether they are different, or if this is a renaming).

I just reran OPL-update a few minutes ago though, so the version seems current.

I've run across several NPL problems that we use in some of our standard homework sets that no longer work, and in fact cause a big problem.

They claim to be placeholders for the same problem, now stored in another location.  The problem is the "other location" they refer to simply refers back to the file.  So when WeBWorK attempts to render these problems it loads the file, which tells it to lead the file, ... creating an infinite loop.  Of course not only are the results bad, but this brings the server to an unfortunate near stall.

I guess there are two issues:

1) appropriate for this forum:  what has gone wrong that the NPL has these self referential problems in it.  Is my install screwed up, or are these just mistakes in the NPL and I've been unlucky enough to run across three of them in half an hour?

2) maybe belonging in a different forum:  should WeBWorK be coded to break out of such infinite loops much sooner?

Here are examples of offending problems:



I'm attaching the file of the first of the three problems above.  All of these files
are similar.  They are almost empty but have an includePGproblem that seems 
to be self-referential.

Anyone know if my NPL installation is screwed up, or if these are just errors.
If they are just errors, how might I identify them more globally.  As it is right
now, every time anyone stumbles on them, they do something nasty to
the server.

thanks,  Hal

In reply to Hal Sadofsky

Re: loops in NPL

by John Jones -
This was a problem for a short time in the NPL.  It was discovered and then fixed the next day.  You must have updated by svn during that day.

If you update from svn and still find a loop like this, report it as a bug and it will be fixed.


In reply to Hal Sadofsky

Re: loops in NPL

by Michael Gage -

Check to see if a self referencing link (alias) was set.  e.g. a reference
to .../OpenProblemLibrary/Rochester which is in the Rochester directory.

These can sometimes be created by accident when setting up and then 
cause infinite loops when the library is searched. 

Take care,