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Every now and again, I want to set the value of a number of properties on an object from a hash, where the method name is the same as the key name, but with a prefix, eg


    $object->set_date( $hash{ date } );

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But how to do this for all the keys in a hash? I've thought of two methods:


Method 1:
---------

for ( keys %hash ) {
    my $method = "set_$_";
    $object->$method( $hash{ $_ } );
}

Method 2:
---------
for ( keys %hash ) {
    $object->${ \"set_$_" }( $hash{ $_ } );
}

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I prefer the second method, because it is shorter, but (1) it is less readable and (2) Perl::Tidy reformats it with a space before the arrow, which still works, but looks rather odd:


    $object ->${ \"set_$_" }( $hash{$_} );

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Which method would you prefer? One of the above, or some other syntax?

(Note: I benchmarked the difference between these two, and while the temp var is slightly faster, the difference is negligible.)


    #!/usr/bin/perl
    use strict;
    use warnings;
    use Benchmark qw(cmpthese);

    package foo;
    {
        sub set_var1 { }
        sub set_var2 { }
        sub set_var3 { }
        sub set_var4 { }
        sub set_var5 { }
    }

    package main;

    my $object = bless {}, 'foo';
    my %hash = map { ( "var$_" => $_ ) } ( 1 .. 5 );

    sub temp_var {
        for ( keys %hash ) {
            my $method = "set_$_";
            $object->$method( $hash{$_} );
        }
    }

    sub deref {
        for ( keys %hash ) {
            $object ->${ \"set_$_" }( $hash{$_} );
        }
    }

    cmpthese( 1_000_000,
              {  temp_var => \&temp_var,
                 deref    => \&deref
              }
    );

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Results:


                 Rate    deref temp_var
    deref    176991/s       --     -18%
    temp_var 215054/s      22%       --

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Update: corrected a typo in Method 2, thanks to zwon for pointing it out

In reply to Formatting dynamic method names by clinton

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