On May 2, 9:40 am, [EMAIL PROTECTED] wrote: > Bad file names, i.e. filenames the OS considers illegal, will cause > functions in the os.path module to raise an error. > > Example: > > import os.path > print os.path.getsize( 'c:/pytest/*.py' ) > > On Windows XP using Python 2.5.2 I get the following traceback: > > Traceback (most recent call last): > File "<string>", line 74, in run_nodebug > File "<Module1>", line 3, in <module> > File "C:\Python\lib\ntpath.py", line 228, in getsize > return os.stat(filename).st_size > WindowsError: [Error 123] The filename, directory name, or volume label > syntax is incorrect: 'c:/pytest/*.py' > > Since there are many places a user can enter a path name (interactively, > via config files, etc) in most applications, is there an os sensitive > function that can be used to detect bad file names? > > As a matter of best practice, how do you wrap your use of file and path > names to prevent unexpected failures? (There has to be a better > alternative than try/except blocks around each use of an os.path > function in one's code?) > > Thanks, > Malcolm
What do you find troubling about try/except? Compare: import os.path path = raw_input("enter a path:") if isvalidpath(path): # this is a made up name print os.path.getsize(path) else: # Do something else To: import os.path path = raw_input("enter a path:") try: print os.path.getsize(path) except WindowsError: # Do something else Now, I can understand if you don't like the "WindowsError" as that is obviously platform specific. The try/except pattern however is the way errors are handled in python and the best and most appropriate way to deal with it. The above example just shows that at the very least there isn't a significant difference in code size between the two methods. I don't know what the equivalent error is called in *nix but assume it is PosixError (it isn't), then it would just be written this way: import os.path path = raw_input("enter a path:") try: print os.path.getsize(path) except (WindowsError, PosixError): # Do something else You don't _always_ need to wrap os.path functions with try/except. You only need to wrap where there is reason to expect that the input might be prone to error. In those cases the alternative is what? wrapping it in a if/else instead? How is that better? Matt -- http://mail.python.org/mailman/listinfo/python-list