In the Shiny Ball Book (Effective Perl Programming) under "Item 26: Pass references instead of copies" there is the "Using local * on reference arguments" subitem (pages 100-101). An example is given: 
sub max_v_local {
  local (*a, *b) = @_;
  my $n = @a > @b ? @a : @b;
  my @result;
 for( my $i = 0; $i < $n; $i++ ) {
   push @result, $a[$i] > $b[$i] ? $a[$i] : $b[$i];
   }
  @result;
  }

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Presumably one would call this as follows: 
my @answer = max_v_local( \@mylist, \@yourlist );

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Can I use this typeglob trick with 'use strict'? If so then read on...

I thought this would be great to use in other circumstances but I keep running into problems. Here's some example code (The typeglob is near the middle in the foreach block; This snippet reads in a CSV file and generates an XML file; @c describes the CSV file; For the curious, grbr is an internal identifier). 

sub test_xml_writer {
    my( @array, $aref );
    my $io = new IO::File '<test.txt' or die( "IO Failure" );
    my $csv = new Text::CSV_XS;
    while( 1 ) {
        $aref = $csv->getline( $io );
        $#{ $aref } > -1 ? push @array, $aref  :  last;
        }
    $io->close();
    
    $io = new IO::File '>test-out.xml' or die "Could not open output f
+ile";
    my $w = new XML::Writer( OUTPUT => $io, DATA_MODE => 1, DATA_INDEN
+T => 2 );
    $w->xmlDecl( undef , 1 );
    $w->startTag( 'assets' );

    foreach ( @array ) {
        $w->startTag( 'machine' );
        my @c = qw( name ip_address snmp_community grbr model_serial )
+;
        local *a = $_;
#        my @a = @{$_};
        $w->dataElement( $c[0], $a[0], src => 'netview' ) if defined $
+a[0];
        $w->dataElement( $c[1], $a[1] ) if defined $a[1];
        $w->dataElement( $c[2], $a[2], type => 'rw' ) if defined $a[2]
+;
        $w->dataElement( $c[3], $a[3], src => 'data' ) if defined $a[3
+];
        $w->dataElement( $c[4], $a[4], src => 'data' ) if defined $a[4
+];    
    
        $w->endTag();
        }

    $w->endTag();
    $w->end();
    $io->close();
    }

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Which gives me the following errors: Note that I have use strict and use warnings and that the code above starts on line 92: 
Variable "@a" is not imported at ./test.pl line 112.
Variable "@a" is not imported at ./test.pl line 112.
Variable "@a" is not imported at ./test.pl line 113.
Variable "@a" is not imported at ./test.pl line 113.
Variable "@a" is not imported at ./test.pl line 114.
Variable "@a" is not imported at ./test.pl line 114.
Variable "@a" is not imported at ./test.pl line 115.
Variable "@a" is not imported at ./test.pl line 115.
Variable "@a" is not imported at ./test.pl line 116.
Variable "@a" is not imported at ./test.pl line 116.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+2.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+2.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+3.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+3.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+4.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+4.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+5.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+5.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+6.
Global symbol "@a" requires explicit package name at ./test.pl line 11
+6.
Execution of ./test.pl aborted due to compilation errors.

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What am I doing wrong? -- Argel

In reply to Confused about typeglobs and references by Argel

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