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Postings from May 2013
I notice that File::stat is core, and currently provides a fairly
spartan set of accessor methods. I have an idea to make it a little
nicer to use, and to allow for some funky additions (likely via CPAN)
Currently lots of code will do something like
use Fcntl qw( S_IFDIR S_IFMT );
if( stat($file)->mode & S_IFMT == S_IFDIR ) ...
or
use Fcntl qw( S_ISDIR );
if( S_ISDIR(stat($file)->mode) ) ....
I'd like to propose a simple addition of these as methods of File::stat:
if( stat($file)->ISDIR ) ...
or maybe S_ISDIR, or isdir or.. dunno. Name isn't important - we can
discuss that.
It would make code a little neater, and most specifically, would
decouple an important POSIXism from the underlying API - namely, that
there's a set of mode bits that encodes the filetype and permissions,
and bitmasking some of them out will yield a number that decides if
it's a directory, etc..
Decoupling that may lead the way to some slightly nicer/better/more
efficient ways to provide a stat()-like function on non-POSIX platforms.
The other thing I was thinking was that currently, this code has to
perform a stat() call for every readdir() reply:
my @dirs = grep { -d } readdir($dirh);
However, if we moved some code around we could allow
my @dirs = grep { stat($_)->isdir } readdir($dirh)
on e.g. Linux to use getdents(3) and provide the d_type magic hint,
somehow, out of readdir(). The stat() can then be a little lazy when
presented with such a magic-overloaded hint, saving the real underlying
stat(2) call for later when another method is called, but if the only
method is something like ->isdir, it can use the type itself. Hey
presto - efficient transparent getdents() wrapping.
Anyway, all of that can be done elsewhere on CPAN; the only question
for core is: should we add these convenience methods? I think we should
as they're tiny, easy to implement, and obviously quite useful for
users to call.
I'm happy to provide a patch if it will be generally accepted.
--
Paul "LeoNerd" Evans
leonerd@leonerd.org.uk
ICQ# 4135350 | Registered Linux# 179460
http://www.leonerd.org.uk/
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