[Python-ideas] Extend the os.stat() result objects with methods like isfile() and isdir()

[MRAB]

On 02/05/2013 17:49, Pieter Nagel wrote:
> I propose adding methods like isfile(), isdir(), islink(), isfifo() and
> so on - basically everything that would currently be done via code like
> "stat.S_ISREG(s.st_mode)".
>
> Please indicate support or not, so I can know whether to draft a PEP and
> work on implementation.
>
> My motivation is twofold:
>
> Firstly, it would make code that needs to interpret stat() results using
> the existing S_ISREG etc. methods in the stat module look cleaner, more
> Pythonic, and less like C code manipulating bitmasks.
>
> Secondly, in a recent discussion on python-dev [1] the issue was raised
> that the stat() call can perform badly under certain situations, and
> that some form of caching of the result of stat() calls is therefore
> desirable.
>
> This proposal makes it easier to do one form of caching stat() results:
> the kind where the result is manually cached by storing it in some
> variable.
>
> Think of code such as:
>
>    if os.path.isfile(f) or os.path.isdir(f):
>      # do something
>
> This will indirectly cause two calls to stat().
>
> Currently, if you want to manually cache that stat call, you'll need to
> write:
>
>    s = os.stat(f)
>    if stat.S_ISREG(s.st_mode) or stat.S_ISDIR(s.st_mode):
>      # do something
>
> This not only looks more convoluted and requires an extra import of
> stat, but it also looks wildly different from the previous code even
> though it basically has the same semantics.
>
> Under my proposal, this could become:
>
>    s = os.stat(f)
>    if s.isfile() or s.isdir():
>      # do something
>
> This proposal is independent of the current PEP 428 Path object
> proposal. However, if accepted, users of PEP 428 Path objects will also
> benefit, since those can also return results of stat() calls.
>
>
+1

It also means not having to import the stat module to get the
strangely-named (to me) constants (why the "S_" prefix? Yes, I do know
why, BTW. :-)).