[Python-ideas] Deprecate str.find

[Cameron Simpson]

On 16Jul2011 22:21, Masklinn <masklinn at masklinn.net> wrote:
| On 2011-07-16, at 21:52 , Terry Reedy wrote:
| > On 7/16/2011 2:46 PM, Terry Reedy wrote:
| >> On 7/15/2011 6:50 PM, Cameron Simpson wrote:
| >>> str.find does not have a failure mode, it has string found and string
| >>> not found.
| >> 
| >> Not finding == failure to find == failure to match an implied re.
| > Indeed, negative values such as -1 are standard error/failure
| > return codes for functions that normally return nonnegative ints and
| > that written in statically typed languages without catchable exceptions
|
| … or type systems worth using. And that's for those which are
| 0-indexed of course, especially for finding sub-sequences.
| 
| And interestingly, the function corresponding to `str.find` in libc
| returns `NULL` in case of failure, not −1 (its return value is a
| pointer to the first occurrence of the needle in the haysack).

Though if you're thinking NULL is equivalent to None (which is often is
conceptually), let's remember that in C NULL is just a pointer value; it
is a sentinal, but not a different type. So NULL here is in some ways
akin to -1 in Python's find return. You still need to test for it; not
all platforms will (for example) segfault if NULL is dereferenced.

Cheers,
-- 
Cameron Simpson <cs at zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

There's no need to worry about death, it will not happen in your lifetime.
        - Raymond Smullyan