IBP banding data system: Internal maintenance specification

This method looks at self.fileName to see if it starts with a location code.

# - - -   B a s e C o m p i l e r . c h e c k F o r L o c a t i o n

    def checkForLocation(self):
        '''See if self.fileName starts with a valid location code.

          [ if (self.fileName starts with LOCATION_PAT) and
            (the matching part is a location code defined in
            self.stationSet) ->
              self.location  :=  the Location from self.stationSet
                                 with that location code
              return self.fileName past the matching part
            else if (self.fileName starts with LOCATION_PAT) and
            (the matching part is not a location code defined in
            self.stationSet) ->
              Log()  +:=  error message(s)
              raise ValueError
            else -> return None ]
        '''

We use the precompiled regular expression LOCATION_PAT to see if the start of self.fileName looks like a location code.

        #-- 1 --
        # [ if self.fileName starts with LOCATION_PAT ->
        #     locCode  :=  the part that matches
        #     rest     :=  the part after the match
        #   else ->
        #     return None ]
        m = LOCATION_PAT.match(self.fileName)
        if  m is None:
            return None
        else:
            locCode = m.group()
            rest = self.fileName[m.end():]

Next we look up locCode in the stations authority object. See Section 8.1, “BaseStationSet.locationLookup()”.

        #-- 2 --
        # [ if locCode is a location code defined in
        #   self.stationSet ->
        #     self.location  :=  the Location object with that code
        #   else ->
        #     Log()  +:=  error message
        #     raise ValueError ]
        try:
            self.location = self.stationSet.locationLookup(locCode)
        except KeyError:
            message = "No such location code: '%s'" % locCode
            Log().error(message)
            raise ValueError, message

        #-- 3 --
        return rest