Steve Holden wrote: > Of course. But onc you (sensibly) decide to use an "if" then there > really isn't much difference between -1, None, () and sys.maxint as > a sentinel value, is there?
Sure there is. -1 is a valid index; None is not. -1 as a sentinel is specific to str.find(); None is used all over Python as a sentinel. If I may digress for a bit, my advisor is currently working on a project that is processing seafloor depth datasets starting from a few decades ago. A lot of this data was orginally to be processed using FORTRAN software, so in the idiom of much FORTRAN software from those days, 9999 is often used to mark missing data. Unfortunately, 9999 is a perfectly valid datum in most of the unit systems used by the various datasets. Now he has to find a grad student to traul through the datasets and clean up the really invalid 9999's (as well as other such fun tasks like deciding if a dataset that says it's using feet is actually using meters). I have already called "Not It." -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
