Request for feedback on my first Python program

[Andreas Jung]

It's nice to see that one of the world most  famous C++ guys uses Python 
too ...welcome :-)

Andreas

--On Donnerstag, 29. Mai 2003 23:14 Uhr -0700 Scott Meyers 
<Usenet at aristeia.com> wrote:

> I'm a C++ programmer who's writing his very first Python program.  This
> means the program is going to be gross, and I apologize for that in
> advance.  I don't really have anybody I can show it to for feedback, so
> I'm hoping I can get some comments here.  If there is a better place for
> me to seek guidance, please let me know.
>
> The program is supposed to read a file containing directory and file
> names, one per line.  (The file can also contain comment and blank lines,
> which should be ignored.)  For each file or directory name, the program
> should print out whether it's a directory, a file, or neither.  That's it.
>
> Here's the code; you may want to hold your nose:
>
>   import sys
>   import os
>   import string
>
>   # Error status codes
>   BadInvocation = 1
>
>   def usage(programName):
>     print "Usage: " + os.path.basename(programName) + " [file]"
>     sys.exit(BadInvocation)
>
>   # Take a list of strings, return an equivalent list where the following
>   # strings have been removed:
>   # - those with no non-whitespace characters
>   # - those whose first non-whitespace character is a "#"
>   def getMeaningfulLines(lines):
>     nonCommentLines = []
>     for i in range(0,len(lines)):
>       try:
>         firstToken = string.split(lines[i])[0]
>         if firstToken[0] != "#":
>           nonCommentLines.append(lines[i])
>       except IndexError:
>         continue
>     return nonCommentLines
>
>
>   # if this language had a main(), it'd be here...
>   if len(sys.argv) != 2: usage(sys.argv[0])
>
>   lines = getMeaningfulLines(open(sys.argv[1]).readlines())
>   for i in lines:
>     print i + " is a ",
>     if os.path.isdir(i): print "directory"
>     elif os.path.isfile(i): print "file"
>     else: print "non-directory and non-file"
>
> In addition to the numerious stylistic gaffes I'm sure I've made, the
> program also doesn't work correctly.  Given this input file,
>
>   d:\
>   d:\temp\foo.py
>
> I get this output:
>
>   d:\
>    is a  non-directory and non-file
>   d:\temp\foo.py
>    is a  non-directory and non-file
>
> Aside from being ugly (how do I get rid of the newline that follows each
> directory or file name?), the problem is that the first entry IS a
> directory and the second one IS a file.  So clearly I'm doing something
> wrong.  Any idea what it is?
>
> Thanks very much in advance.
>
> Scott
> --
> http://mail.python.org/mailman/listinfo/python-list