"Using a hash as a reference is deprecated" -- Baloney !

[Anonymous Monk]

Wait a minute --- what's wrong with these lines ?! These look perfectly fine!

$WAI is an object, which I call getMem() which returns a hashref, I then address a piece of the hashref with ->{'MemTotal'} and take that inside the object's converter function kBToMB().

Is this bad ?? What's a better way to achieve the same thing?

----------------------------

sub get_memory_tot {
        return $WAI->kBToMB( %{$WAI->getMem()}->{'MemTotal'} );
}

sub get_memory_free {
        return $WAI->kBToMB( %{$WAI->getMem()}->{'MemFree'} );
}

sub get_swap {
        return $WAI->kBToMB( %{ $WAI->getMem() }->{'SwapTotal'});
}

[kennethk]

If getMem() is returning a hash reference, then you are dereferencing the hashref into a hash with %{ ... } and then dereferencing a second time using The Arrow Operator, thus the warning. The preferred syntax would be:

sub get_memory_tot {
        return $WAI->kBToMB($WAI->getMem()->{'MemTotal'} );
}

sub get_memory_free {
        return $WAI->kBToMB( $WAI->getMem()->{'MemFree'} );
}

sub get_swap {
        return $WAI->kBToMB( $WAI->getMem()->{'SwapTotal'});
}

See perlref and/or perlreftut for more explanation.

[NetWallah]

Paraphrasing from from perlop:The left side of the "->" ( infix dereference operator) must be a REFERENCE to ....

In your case, you are supplying a HASH (Not a reference).

Just get rid of the %{...} , and you will have a (Hash) reference.

             return $WAI->kBToMB( $WAI->getMem()->{MemTotal} );

(No need for quotes inside {} ).

[ikegami]

Due to a bug in Perl,

%foo->{bar}

gets interpreted as a

(\%foo)->{bar}

->{bar} expects a reference, and thus a scalar, so it should be interpreted as

scalar(%foo)->{bar}

The deprecation warning was added in anticipation of getting this bug fixed.

Since

%{$WAI->getMem()}->{'MemTotal'}

is getting interpreted as

\%{$WAI->getMem()}->{'MemTotal'}

you could use that, or you could shorten it to

$WAI->getMem()->{'MemTotal'}

Now where's this baloney you promised? I'm hungry!

Update: Fixed bad curlies matching in second half.

[Anonymous Monk]

Awesome. Excellent explanation, I had no idea this was a planned bugfix. Thanks everyone ! Here's the promised "baloney" :)

Balogna ("baloney") and cheese:


                    _.---._
                _.-~       ~-._
            _.-~               ~-._
        _.-~                       ~---._
    _.-~                                 ~\
 .-~                                    _.;
 :-._                               _.-~./
 }-._~-._                   _..__.-~_.-~ )
 `-._~-._~-._              /   ...-~H.-~
     ~-nad.._\.        _.-~ .::::  //
         ~-. \`--...--~ _.-~__...==~
            \.`--...---+-~~~~~
              ~-..----~

How about a deli style turkey sandwich (damn I'm hungry now!):

                    _.---._
                _.-~       ~-._
            _.-~               ~-._
        _.-~                       ~---._
    _.-~                                 ~\
 .-~                                    _.;
 :-._                               _.-~ ./
 `-._~-._                   _..__.-~ _.-~
  /  ~-._~-._              / .__..--~----._
 \_____(_;-._\.        _.-~_/       ~).. . \
    /(_____  \`--...--~_.-~______..-+_______)
  .(_________/`--...--~/    _/nad        /\
 /-._     \_     (___./_..-~__.....__..-~./
 `-._~-._   ~\--------~  .-~_..__.-~ _.-~
     ~-._~-._ ~---------'  / .__..--~
         ~-._\.        _.-~_/
             \`--...--~_.-~
              `--...--~


Gotta have something to wash that down with...

                                                           _
                                                          //
                                                         //
                                         _______________//__
                                       .(______________//___).
                                       |              /      |
                                       |. . . . . . . / . . .|
                                       \ . . . . . ./. . . . /
                                        |           / ___   |
                    _.---._             |::......./../...\.:|
                _.-~       ~-._         |::::/::\::/:\::::::|
            _.-~               ~-._     |::::\::/::::::X:/::|
        _.-~                       ~---.;:::::::/::\::/:::::|
    _.-~                                 ~\::::::n::::::::::|
 .-~                                    _.;::/::::a::::::::/
 :-._                               _.-~ ./::::::::d:::::::|
 `-._~-._                   _..__.-~ _.-~|::/::::::::::::::|
  /  ~-._~-._              / .__..--~----.YWWWWWWWWWWWWWWWP'
 \_____(_;-._\.        _.-~_/       ~).. . \
    /(_____  \`--...--~_.-~______..-+_______)
  .(_________/`--...--~/    _/           /\
 /-._     \_     (___./_..-~__.....__..-~./
 `-._~-._   ~\--------~  .-~_..__.-~ _.-~
     ~-._~-._ ~---------'  / .__..--~
         ~-._\.        _.-~_/
             \`--...--~_.-~
              `--...--~

credit to : Nate / DAC for the artwork !

[LanX]

Well you are overcompensating! ;)

Either $WAI->getMem()->{'SwapTotal'} or (which nobody mentioned yet)  %{ $WAI->getMem() }{'SwapTotal'} but not both.

Old perl versions allowed to write %hash->{key} but as you see it's deprecated now.