On 02/19/2015 12:10 AM, Chris Angelico wrote:
On Thu, Feb 19, 2015 at 3:44 PM, Jason Friedman <jsf80...@gmail.com> wrote:
I have need to search a directory and return the name of the most recent
file matching a given pattern. Given a directory with these files and
timestamps,
q.pattern1.abc Feb 13
r.pattern1.cdf Feb 12
s.pattern1.efg Feb 10
t.pattern2.abc Feb 13
u.pattern2.xyz Feb 14
v.pattern2.efg Feb 10
calling my_function("/path/to/dir", "pattern1") will return q.pattern1.abc
and calling my_function("/path/to/dir", "pattern2") will return
u.pattern2.xyz.
That seems reasonable, and well-defined.
My question is, what would be a reasonable behavior/result/return value if:
1. "/path/to/dir" does not exist or is not readable
Raise an exception. Or, better still, just allow the exception to bubble.
2. no files match the given pattern
Either return None, or raise an exception, depending on how "normal"
this state is. Is it simply a matter of "you asked for something, but
you got nothing"? Then return None. Is it a really unusual situation
that should basically never happen? Then raise an exception, so you
get an instant report with no wondering "why am I getting these
strange TypeErrors".
Also, what would be a reasonable name for such a function?
newest_file_matching() seems decent. Remember, it doesn't have to be
especially short.
Consider returning a list of files, sorted by datestamp. Return an
empty list if there are no matches. That way, the user can find the
newest, the oldest, can check if any match, and so on, all by how it
manipulates the list.
if result: check whether there are any matches
newest = result[0]
oldest = result[-1]
Your code probably has to build the list anyway, to find the newest. So
why not just return it, and let the caller decide which part(s) to keep.
--
DaveA
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