To conform with the documentation, csv.DictReader 
(and possibly DictWriter) should accept keyword 
arguments to specify a dialect on the fly and forward 
them to its reader instance: 
 
class DictReader: 
    def __init__(self, f, fieldnames, restkey=None, 
restval=None, 
                 dialect="excel", *args, **kwd): 
        self.fieldnames = fieldnames    # list of keys for 
the dict 
        self.restkey = restkey          # key to catch long 
rows 
        self.restval = restval          # default value for 
short rows 
        self.reader = reader(f, dialect, *args, **kwd)