When writing text-oriented command line programs in Python, I often want to read either all the files passed on the command line, or (XOR) standard input (like Unix cat does, or Perl's <>). So, I say
if len(args) == 0: # result from optparse
input = sys.stdin
else:
input = itertools.chain(*(open(a) for a in args))
Is this the Pythonic way of doing this, or did my miss some part of the library?
You need fileinput.
A standard use case is:
import fileinput
for line in fileinput.input():
process(line)
open("", 'r').read()) there is no built-in way to do that with the fileinput stdlib module. Unless I'm mistaken in reading the docs.
allText="" before the for loop, and allText += line in it.
read() method. However, for concatenating lines, adding up lines is officially not recommended. It is much more efficient to collect them in a list and then joining them with "".join(lines)—this is the officially recommended method.In Python 3, argparse handles filetype objects very nicely. It's an extremely powerful module and the docs come with many examples, so it's easy to quickly write the code you want. (How Pythonic!)
You may also benefit from this StackOverflow question about using argparse to optionally read from stdin.
