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odd number of elements in hash

I'm trying to debug some perl code written by someone else. It has a line:

Code:

Daemon::Generic->newdaemon(

  progname    => 'mycach',

  configfile  => '/ekb/mycach.conf',

  pidfile    => '/var/run/mycach.pid'

);

When run, I get:

Code:

Odd number of elements in hash assignment at /usr/local/share/perl5/Daemon/Generic.pm line 22.

Line 22 is:

Code:

my (%args) = @_;

Run under debug it shows:

Code:

Daemon::Generic::newdaemon('Daemon::Generic', 'progname', 'mycach', 'configfile', '/ekb/mycach.conf', 'pidfile', '/var/run/mycach.pid')

which seems to show 'Daemon::Generic' is thrown in there with no element for some reason. The system has Daemon::Generic 0.82 installed. Anyone have some suggestions?

Thanks!

Hi,

it seems that you have to use an even number of arguments to the "constructor" function. Namely pairs of key and value, look here http://perldesignpatterns.com/?NamedArguments

Quote:

my (%args) = @_;

means to use a hash for the parameters.

An explanation of the module is here at cpan http://search.cpan.org/dist/Daemon-G...E_USAGE_OUTPUT

Markus

Quote:

Originally Posted by bradvan (Post 4830926)

I'm trying to debug some perl code written by someone else. It has a line:

Code:

Daemon::Generic->newdaemon(

  progname    => 'mycach',

  configfile  => '/ekb/mycach.conf',

  pidfile    => '/var/run/mycach.pid'

);

When run, I get:

Code:

Odd number of elements in hash assignment at /usr/local/share/perl5/Daemon/Generic.pm line 22.

Line 22 is:

Code:

my (%args) = @_;

Run under debug it shows:

Code:

Daemon::Generic::newdaemon('Daemon::Generic', 'progname', 'mycach', 'configfile', '/ekb/mycach.conf', 'pidfile', '/var/run/mycach.pid')

which seems to show 'Daemon::Generic' is thrown in there with no element for some reason. The system has Daemon::Generic 0.82 installed. Anyone have some suggestions?

Thanks!

I think you should write

Code:

my %args = @_;

Quote:

Originally Posted by Sergei Steshenko (Post 4831150)

I think you should write

Code:

my %args = @_;

:doh: I was missing this when I wrote my above reply. So the problem here is that the parenthesis put the hash %args into a scalar context which makes no sense for Perl.

Markus

Ah, good catch! That means there must be an error in the CPAN module. Thanks!

Rats, that wasn't the problem. Adding or removing parenthesis doesn't make a difference. The problem seems to be when the call is made:

Code:

Daemon::Generic->newdaemon (

  progname    => 'mycach',

  configfile  => '/ekb/mycach.conf',

  pidfile    => '/var/run/mycach.pid'

);

perl is passing:

Code:

('Daemon::Generic', 'progname', 'mycach', 'configfile', 'ekb/mycach.conf', 'pidfile', '/var/run/mycach.pid')

and not

Code:

('progname', 'mycach', 'configfile', 'ekb/mycach.conf', 'pidfile', '/var/run/mycach.pid')

Notice the 'Daemon::Generic' is at the head of the list and thus makes an odd number. Any ideas on why 'Daemon::Generic' is included and how to get rid of it?

Regards,

Brad

I temporarily got around it by adding in the Daemon::Generic sub newdaemon procedure (before the my (%args) line:

Code:

if (($#_ + 1) % 2) {

  shift(@_);

}

which makes it work. I'd still like to find out why the script is adding the 'Daemon::Generic' to the call if anyone knows.

Regards,

Brad V

Quote:

Originally Posted by bradvan (Post 4832575)

Rats, that wasn't the problem. Adding or removing parenthesis doesn't make a difference. The problem seems to be when the call is made:

Code:

Daemon::Generic->newdaemon (

  progname    => 'mycach',

  configfile  => '/ekb/mycach.conf',

  pidfile    => '/var/run/mycach.pid'

);

perl is passing:

Code:

('Daemon::Generic', 'progname', 'mycach', 'configfile', 'ekb/mycach.conf', 'pidfile', '/var/run/mycach.pid')

and not

Code:

('progname', 'mycach', 'configfile', 'ekb/mycach.conf', 'pidfile', '/var/run/mycach.pid')

Notice the 'Daemon::Generic' is at the head of the list and thus makes an odd number. Any ideas on why 'Daemon::Generic' is included and how to get rid of it?

Regards,

Brad

Perl is doing "the right thing" (tm).

My point is that the "->" notation prescribes this behavior - this is how Perl OO model works. The idiom is:

Code:

sub foo

  {

  my $self = shift;

  # deal with the rest of args in @_

  # the code doing the job is here

  # methods are called as $self->method_name(...)

  }

If you do not want this behavior, you should use this:

Code:

Daemon::Generic::newdaemon(...)

form of call.

Ahh, OK, thanks for the education! :) I'll make the change.

Thanks Again!