Re: find function

As I prefer functional style programming over procedural, I never really liked File::Find's "global vars interface".

So being faced with the problem of looking through some directory tree i will use File::Find, but when it's necessary to tweak the process of its search, I prefer using the preprocess CODEref.

As I don't see that covered a lot in the resources given by PodMaster, I'd like to give an (overly explicit) example:

use strict;
use warnings;
use File::Find;

sub wanted {
  my $file = $File::Find::name;
  print "$File::Find::name is a ", -d $file ? 'directory' : 'file', $/
+;
}

sub filter {
  grep {
    my $file = "$File::Find::dir/$_";
    if (-d $file) {
      my $depth = $file =~ s#/#/#g;
      if ($depth > 3) {
        print "Depth > 3 in $file ... skipping\n";
        0;  # return as grep result for this $file
      } else {
        1;  # concider this to recurse into
      }
    } else {
      1;   # include non-dirs
    }
  } grep !/^\.\.?$/, @_;
}

find(
  {
    no_chdir => 1,
    wanted => \&wanted,
    preprocess => \&filter,
  },
  shift

);
[download]

An additional advantage of this approach over using/setting File::Find::prune, is that it also works with bydepth => 1.

Also note, that I generally refuse to let find do the chdir thing, because that tends to confuse me. ;-)

Just my two eurocent

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Re^2: find function by Anonymous Monk on Dec 06, 2005 at 16:09 UTC
As I prefer functional style programming over procedural, I never really liked File::Find's "global vars interface" That's kind of funny. File::Find has one of the most functional interfaces of any core module I can think of. I mean, its 'find' subroutine's first argument is a function. Granted, it does use funky globals instead of @_ to pass arguments to that function, but I think that's an orthogonal to its functional-ness.	[reply]
Re^3: find function by pKai (Priest) on Dec 06, 2005 at 16:40 UTC
`wanted` (like `find`) itself can never be "functional", since its return value ist either discarded or nonexistent, relying entirely on side-effects for their "function" ;-) For a clarification what program language designer nick-name "functional" the wikipedia article on Functional_programming is a good start.	[reply] [d/l] [select]