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Odd number of elements in anonymous hash

by Anonymous Monk
on Jun 09, 2016 at 16:01 UTC ( #1165231=perlquestion: print w/replies, xml ) Need Help??

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!

I am trying to understand why I am getting this warning - "Odd number of elements in anonymous hash" - since the variable "$attached" has been initialized before it
gets to the hash. I only need these values in the hash if "$code" is true, otherwise it should be nothing there.
Where/what am I missing, if someone could take a look at this sample code I am posting:
... for my $email (@mail) { my $attached = ($code) ? "attach_path => '$file_name',attach_filena +me => '$file_name',attach_type => 'application/txt'," : ''; my $success = email( { to => $email, from => $from, from_name => $name, subject => $subject, body => $body, $attached } ); } ...
Thanks for looking!

Replies are listed 'Best First'.
Re: Odd number of elements in anonymous hash
by toolic (Bishop) on Jun 09, 2016 at 16:11 UTC
    my $href = { to => $email, from => $from, from_name => $name, subject => $subject, body => $body, }; if ($code) { $href->{attach_path} = $file_name; $href->{attach_filename} = $file_name; $href->{attach_type} = 'application/txt'; } my $success = email($href);
Re: Odd number of elements in anonymous hash
by tangent (Vicar) on Jun 09, 2016 at 16:06 UTC
    $attached is a hash reference so you need to dereference it, and default to an empty hash ref if $code is false:
    my $attached = ($code) ? "attach_path => '$file_name',attach_filena +m +e => '$file_name',attach_type => 'application/txt'," : {}; my $success = email( { to => $email, from => $from, from_name => $name, subject => $subject, body => $body, %$attached } );
    Update: as pryrt points out, $attached is not a hash reference (it is a string) but can easily be made into one - see my further example below.

      but when $code is true, $attached is a STRING in the OP code. And I couldn't get test code to dereference the string version to include in the new hashref.

      Here's some example code which tries and dumps both code=0 and 1:

      #!perl use strict; use warnings; use Data::Dumper; for my $code (0 .. 1) { my $attached = $code ? { attach_path => 'etc' } : {}; my $args = { to => 'to email', from => 'from email', %$attached }; print Dumper($args); }

        Yes, actually $attached is a single string whether $code is true or false: in the latter case, it’s the empty string. And that means you get a key/value pair in which the string $attached is the key, and the value is undef — which gives the “Odd number of elements” warning.

        The solution is to eval the string:

        #! perl use strict; use warnings; use Data::Dump; my $body = 'Hello!'; my $code = 1; my $email = 'addressee'; my $file_name = 'unknown'; my $from = 'sender'; my $name = 'A Nonny Mouse'; my $subject = 'Greeting'; my $attached = $code ? "attach_path => '$file_name', " . "attach_filename => '$file_name', " . "attach_type => 'application/txt'," : ''; my $success = { to => $email, from => $from, from_name => $name, subject => $subject, body => $body, eval $attached, }; dd $success;

        Output:

        2:21 >perl 1655_SoPW.pl { attach_filename => "unknown", attach_path => "unknown", attach_type => "application/txt", body => "Hello!", from => "sender", from_name => "A Nonny Mouse", subject => "Greeting", to => "addressee", } 2:21 >

        Hope that helps,

        Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

        I didn't notice it was a string, thanks. So it could be done like this, though toolic's answer is cleaner.
        my $attached = $code ? { attach_path => $file_name, attach_filename => + $file_name, attach_type => 'application/txt' } : {};
      I think $attached should be a hash ref.
      use strict; use warnings; use Data::Dumper; my $code = 1; my $file_name = 'my_file_name'; my $email = 'to@address.com'; my $from = 'from@address.com'; my $from_name = 'Me'; my $subject = 'try_me'; my $body = 'Here is my message.'; my $attached = ($code) ? { attach_path => $file_name, attach_filename => $file_name, attach_type => 'application/txt', } : {} ; my %args = ( to => $email, from => $from, from_name => $from_name, subject => $subject, body => $body, %$attached ); my $success = email(%args); sub email { # Display arguments; my %arg_hash = @_; print Dumper(\%arg_hash); ... } OUTPUT: $VAR1 = { 'attach_path' => 'my_file_name', 'from' => 'from@address.com', 'subject' => 'try_me', 'from_name' => 'Me', 'attach_filename' => 'my_file_name', 'to' => 'to@address.com', 'attach_type' => 'application/txt', 'body' => 'Here is my message.' }; Unimplemented at C:\Users\Bill\perl\monks\email.pl line 38
      Bill

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