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Re^3: Insert into element into arrays ref (updated)

by AnomalousMonk (Bishop)
on Aug 22, 2019 at 18:47 UTC ( #11104871=note: print w/replies, xml ) Need Help??


in reply to Re^2: Insert into element into arrays ref
in thread Insert into element into arrays ref

One way (update: see the Perl Data Structures Cookbook):

c:\@Work\Perl\monks>perl use strict; use warnings; use Data::Dumper; my $data1 = [ { 'NAME' => 'PAUL DY', 'DATE' => '2009-05-05', 'NUMBER' => '00001', }, { 'NAME' => 'ANTHONY RD', 'DATE' => '2012-01-07', 'NUMBER' => '00003', }, { 'NAME' => 'RUTH RD', 'DATE' => '2018-01-07', 'NUMBER' => '00023', }, ]; my $data2 = [ { 'CODE' => 'X11', } ]; foreach my $hashref (@$data1) { %$hashref = (%$hashref, %{ $data2->[0] }); } print Dumper $data1; __END__ $VAR1 = [ { 'NAME' => 'PAUL DY', 'DATE' => '2009-05-05', 'CODE' => 'X11', 'NUMBER' => '00001' }, { 'NAME' => 'ANTHONY RD', 'DATE' => '2012-01-07', 'CODE' => 'X11', 'NUMBER' => '00003' }, { 'NAME' => 'RUTH RD', 'DATE' => '2018-01-07', 'CODE' => 'X11', 'NUMBER' => '00023' } ];

Update 1: Note that using this method, if there is a key in the hash referent of the single element of the  $data2 array referent that is the same as one in a hash referent of any  $data1 array referent, the value of the former will silently overwrite the value of the latter. (Update: For instance, see what happens if  $data2 happens to be
    my $data2 = [ { 'CODE' => 'X11',  'NAME' => 'JONES', } ];
instead. (Update: This exact problem is discussed more clearly in the FAQ referenced by BillKSmith here.))

Update 2: Here's a testing framework for playing around with other approaches. See Test::More, Test::NoWarnings.

c:\@Work\Perl\monks>perl use strict; use warnings; use Test::More 'no_plan'; use Test::NoWarnings; use Data::Dumper; my $data1 = [ { 'NAME' => 'PAUL DY', 'DATE' => '2009-05-05', 'NUMBER' => '00001', }, { 'NAME' => 'ANTHONY RD', 'DATE' => '2012-01-07', 'NUMBER' => '00003', }, { 'NAME' => 'RUTH RD', 'DATE' => '2018-01-07', 'NUMBER' => '00023', }, ]; my $data2 = [ { 'CODE' => 'X11', } ]; foreach my $hashref (@$data1) { %$hashref = (%$hashref, %{ $data2->[0] }); } my $expected = [ { 'NAME' => 'PAUL DY', 'DATE' => '2009-05-05', 'NUMBER' => '00001', 'CODE' => 'X11', }, { 'NAME' => 'ANTHONY RD', 'DATE' => '2012-01-07', 'NUMBER' => '00003', 'CODE' => 'X11', }, { 'NAME' => 'RUTH RD', 'DATE' => '2018-01-07', 'NUMBER' => '00023', 'CODE' => 'X11', }, ]; is_deeply $data1, $expected, 'success!'; done_testing; __END__ ok 1 - success! 1..1 ok 2 - no warnings 1..2


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