I'm attempting to pass a database handle to a subroutine. Searches around here return posts that say "It just works." And as I review my code it seems I'm doing the RightThing(tm)

Please point out what I am doing wrong. Update: moritz quickly identified the problem. You probably can too. If you can't spot it right off, then you have a nice little exercise to work.

I've created a small database derived from US Census Gazetteer data. For each county in the US it contains, among other bits, the FIPS ID and latitude/longitude center point. The point of the code is take an arbitrary lat/long coordinate and determine which counties are "nearby". The code in which I set things up: 

!/usr/bin/perl
use strict;
use warnings;
use lib 'lib';
use Geo;

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use autodie;
use DBD::SQLite;
use Data::Dumper;
use lib 'lib';
use Geo;


my $dbh = DBI->connect(
                "dbi:SQLite:dbname=us_counties.db",
                "",
                "",
                { RaiseError => 1, AutoCommit => 1 },
                );

my $states = $dbh->selectall_hashref( "SELECT id, code FROM state", 'i
+d' );

my $range = .3;   # at US latitudes .3 degree is about 20 miles of sur
+face dist

while(<DATA>) {
        chomp;
        s/"//g; 

        my ($lat,$long) = split /,/;

        my $range = .3;   # at US latitudes .3 degree is about 20 mile
+s of surface distance

        my $county_ref = Geo::find_near_counties( $dbh, $lat, $long, $
+range );

        my $print_stuff = defined $county_ref ?  scalar @$county_ref :
+ "None found ";
        print $print_stuff, " counties found for $lat and $long\n";

}

__DATA__
85,-110
46,-115
27,-81
43,-74
45,-93
48,-104
40,-85

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The lib/Geo.pm in which I'm storing find county "logic": 
package Geo;

sub find_near_counties {

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        my (  $dbh, $lat, $long, $range ) = @_;

        my $increment = .3;
        my @sql_parms =  ( $lat - $range, $lat + $range, $long - $rang
+e, $long + $range ) ;
        my $query = "SELECT fips FROM county WHERE latitude  > ? AND l
+atitude  < ? AND longitude > ? AND longitude < ? ";

        my $county_ref = $dbh->selectcol_arrayref($query, {}, @sql_par
+ms );

        if( ! scalar @$county_ref ) {
                if ( $range > 3 ) { 
                        return undef;
                }
                return find_near_counties( $lat, $long, $range+$increm
+ent );
        }

        return $county_ref;
}
1;

[download]
Running that code results in "Can't call method "selectcol_arrayref" without a package or object reference at lib/Geo.pm line 10, <DATA> line 1."

Though comments on my proto-modularization will be appreciated I'm really here to resolve how to pass the database handle into the sub routine.

So what is my blind spot in passing $dbh?


Be Appropriate && Follow Your Curiosity

In reply to Passing $dbh to subroutine - cluestick whack needed by mikeraz

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