I have to hack some reports together with running totals. I was wondering if there was some efficient way of accumulating fields in an upward-compatible manner -- that is, should I have to add another column I have to change as little code as possible.

I was wondering if I could coax += into being distributive across a hash slice, so I could do the following:

#! /usr/bin/perl -w

use strict;

my( %totals, %delta );
my @fields = qw/foo bar/;
@totals{ @fields } = ( 10, 20 );
@delta{ @fields }  = ( 5, 6 );

# the wish
# @totals{ @fields } += @delta{ @fields };

# the reality
$totals{$_} += $delta{$_} foreach( @fields );

use Data::Dumper;
print Dumper( \%totals );

[download]

Of course in both cases the code is not dependent on the exact fields used, so the main goal has been achieved, but I find the reality code a little ugly. I was wondering if there was some other elegant method of doing this that escapes me. The fields are already in a hash, as I am using DBI's fetchrow_hashref.


--
g r i n d e r

In reply to Using += in array context by grinder

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