Bob Faist’s Blog

Say you need to recurse through a directory and it’s subdirectories for files. Think File::Find. Say you need to query a database for each file you find during the recursive search. Think closure. The “wanted” function reference that is passed to the “find()” function does not except arguments but you need to access data that is outside the scope of this “wanted” function.

The scope of the database handle makes it invisible to the “process_files” function. A closure seems to be a good solution to providing access to it.

package MyPackage;

use strict;
 use base 'MyAppBase';
 use File::Find;

sub run {

 my $self = shift;
 my $dbh = $self->database(); # active DBI connection handle
 my $conf = $self->conf();

sub get_dbh { return $dbh; } # Closure

my $dir_to_search = $conf->{foo_dir};

find(\&process_files, ($dir_to_search));

}

sub process_files {

 my $in_file = $File::Find::name;return unless -f $in_file;

my $dbh = get_dbh(); # use closure

my $sql = "SELECT * FROM TABLE WHERE FILENAME = ?";

my $sth = $dbh->prepare_cached($sql);

$sth->execute($in_file);

my $dbrec = $sth->fetchrow_hashref();

}