On Mon, Sep 28, 2009 at 11:03 PM, Chris Adamson <chris.adam...@mcri.edu.au> wrote: > Hello, > > I am writing code that cycles through files in a directory and for each file > it writes out another file with info in it. It appears that as I am > iterating through the list returned by os.listdir it is being updated with > the new files that are being added to the directory. This occurs even if I > reassign the list to another variable. > > Here is my code: > > fileList = os.listdir(temporaryDirectory) > > for curFile in fileList: > # print the file list to see if it is indeed growing > print FileList > fp = file(os.path.join(temporaryDirectory, "." + curFile), 'w') > # write stuff > fp.close() > > Here is the output: > > ['a', 'b', 'c'] > ['a', 'b', 'c', '.a'] > ['a', 'b', 'c', '.a', '.b'] > ['a', 'b', 'c', '.a', '.b', '.c'] > > So the list is growing and eventually curFile iterates through the list of > files that were created. I don't want this to happen and it seems like a bug > because the fileList variable should be static, i.e. not updated after being > assigned. > Even if I assign fileList to another variable this still happens. Any ideas?
Copy the list instead? Python uses call-by-object, so assignment to a variable doesn't cause copying, you must do so explicitly: fileList = os.listdir(temporaryDirectory)[:] Although this behavior (bug?) you're running into definitely seems like ought to be mentioned in the docs. File a bug perhaps? Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
