Decorator for PSSE's psspy module functions

raisePsspyError.py

def raisePsspyError(psspyFunc):
    """This decorator raises a python exception whenever a psspy
       function returns an ierr that is not 0. """
    def callPsspyFunc(*args, **kwargs):
        ans = psspyFunc(*args, **kwargs)
        if type(ans) is tuple:
            ierr = ans[0]   # ierr is always first element of tuple
        elif type(ans) is int:
            ierr = ans      # function only returns ierr
        else:
            raise Exception("Unkonwn return type %s." % type(ans))
        if ierr != 0:
            # Find all the errors documented in the doc string
            errDoc = psspyFunc.__doc__[psspyFunc.__doc__.find('IERR = 0'):]
            errs = {}
            for errStr in errDoc.split('\n'):
                try:
                    errNum = errStr.split('=')[1].strip()[0]
                    errDesc = errStr.split('=')[1].strip()[2:]
                    errs[int(errNum)] = errDesc
                except:
                    pass
            msg = "psspy." + psspyFunc.__name__ + " generated ierr = " + \
                str(ierr) + ": " + errs[ierr]
            raise Exception(msg)
        else:
            return ans
    return callPsspyFunc

# Apply our decorator to all psspy function which return an ierr
import types
for k,v in vars(psspy).items():
    if isinstance(v, types.FunctionType):
        if v.__doc__.find('IERR = 0') > 0:
            vars(psspy)[k] = raisePsspyError(v)

if __name__ == '__main__':
    import psspy
    psspy.case(r"nonexistantFile.sav")  # Will raise a python exception instead
                                        #  of just going mairly on its way

See https://psspy.org/psse-help-forum/question/1107/raise-psspy-ierr-as-python-exception/ for additional discussion

This is great @jsexauer. I normally run my scripts with

psspy.throwPsseExceptions = True

enabled near the top of the script. With a few small changes, I managed to get your code working with Psse exception types.

Here is the version for when using psspy.throwPsseExceptions = True
https://gist.github.com/jtrain/6519794#file-raisepsspyerror-py

That is a good synergy of my method and the psspy.throwPsseExceptions method. I didn't know about psspy.throwPsseExceptions when I did wrote this; its a cool feature.