Preprocess should work by returning empty, unless some condition is met. This is not right.

I've played a bit with this option before. When File::Find enters a new directory, it does a readdir(). The output of that readdir() is what goes into the preprocess routine. What you return is a) filtered version of that or perhaps even b) a sorted version of that. If you take a directory name out of this list, find() will not follow down that path (useful for pruning off a directory branch).

I'm not sure that using the preprocess option will make any significant difference in performance in this case. Depends upon how many files are in the /advanced/ directories.

As a trick, there is a special variable _, (note not $_). When a file test is done, this causes a stat(), in this case using the _ will cause the file test info from the -f test to be re-used. This will make a performance difference - stat() is not a quick operation. There are some "yeah but's concerning various types of links - I forget the details right now, but usually this is not an issue.

Didn't test this, but I think this will work...if I got my unless logic right.

Update: Ooops, looked again it appears the the below should be changed, OP wants to process .log files and follow all directories that aren't "advanced". 

sub preprocess {

   my @to_return;
   foreach (@_)
   {
      #don't follow down advanced directory paths
      #Do call wanted() on .log files (and any directory not
      #underneath an "advanced" one
       push @to_return, $_ 
          if  ( ( -f   and  /\.log$/ ) or
                !( -d _ and /advanced/) );
    }
    return @to_return;
}

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In reply to Re^2: File::find preprocess problem by Marshall
in thread File::find preprocess problem by nemesdani

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