On 3/22/11 9:06 AM, Bradley Hintze wrote:
Hi,
I just started with argparse. I want to simply check the extension of
the file that the user passes to the program. I get a ''file' object
has no attribute 'rfind'' error when I use
os.path.splitext(args.infile). Here is my code.
import argparse, sys, os
des = 'Get restraint definitions from probe.'
parser = argparse.ArgumentParser(description=des)
parser.add_argument('infile', nargs='?', type=argparse.FileType('r'))
# parser.add_argument('outfile', nargs='?', type=argparse.FileType('w'),
# default=sys.stdout)
args = parser.parse_args()
# print args.infile.readlines()
print basename, extension = os.path.splitext(args.infile)
There may be a better way to check extensions using argparse.
The type= argument should be a callable that either coerces the string to an
appropriate object or raises a ValueError if the string is unacceptable.
FileType() is a convenient callable for opening readable or writable files; when
called, it returns a regular file object, not the filename, as you saw from the
exception you got. It does not do any validation.
You can add validation very easily:
class TxtFile(argparse.FileType):
def __call__(self, string):
base, ext = os.path.splitext(string)
if ext != '.txt':
raise ValueError('%s should have a .txt extension' % string)
return super(TxtFile, self).__call__(string)
...
parser.add_argument('infile', type=TxtFile('r'))
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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