Can I pass mix type of optional arguments to a subroutine?

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I am trying to pass a hash and optional list of variables to a subroutine in hash but its not working. Could you please correct below sample code to help me with the approach?

My sample code looks like

#!/bin/env perl
use warnings;
use strict;
use Data::Dumper;
my %h1 = ( a=> 2, b=>3);
sub sum {
   my $var1=shift;
   my $var2=shift;

   my %hash1=@_;
   #my($a,$b)=@_;
   my $i=0;
   foreach my $val (keys %hash1) {
        $i=$i+$hash1{$val};
   }
   if ( not defined $var2 ) {
        return ($i+$var1);
   } else {
        return ($i+$var1+$var2);
   }
}
my $c=sum(3,%h1);
print $c;

Subroutines and Parameter Passing, The first subroutine, sub1, does not have passed parameters but uses some show various techniques including return values, mixed parameter types, and the use and Reference Variables $var1 = 13; # Global Scalar Variable $var2 = 51;​  Passing Arguments to a Subroutine. You can pass various arguments to a subroutine like you do in any other programming language and they can be acessed inside the function using the special array @_. Thus the first argument to the function is in $_[0], the second is in $_[1], and so on.

Thanks everyone. This is how we can pass optional arguments to a subroutine in perl with type mixed

#!/bin/env perl
use warnings;
use strict;
use Data::Dumper;
my %h1 = ( a=> 2, b=>3); 
sub sum {

   my ($hash1,$var1,$var2)=@_;
   #my($a,$b)=@_;
   my $i=0;
   foreach my $val (keys %{$hash1}) {
   $i=$i+$hash1->{$val};
   }
   if (defined $var2 ) {
    return ($i+$var1+$var2);
   } else {
    return ($i+$var1);
   }
}

my $c=sum(\%h1,3);
print $c;

Please correct me if I missed something.

Regards, Divesh

Optional Arguments, Programming with Mixed Languages Overview · Standard Fortran and Dummy arguments can be made optional if they are declared with the OPTIONAL attribute. Arguments can be passed out of order, but must be ! associated with the Same as CALL SUB2() END SUBROUTINE SUB1 SUBROUTINE  For arguments of CHARACTER type, the character length is passed as a hidden argument at the end of the argument list. For deferred-length strings, the value is passed by reference, otherwise by value. The character length has the C type size_t (or INTEGER(kind=C_SIZE_T) in Fortran).

#!/usr/bin/perl
use warnings;
use strict;
use JSON;
use feature qw(say);

args_in( 'test', { foo => 'bar' }, ["one", "two", "three"] );

sub args_in {
  my $args_aref = parse_args( @_ );
  say to_json $args_aref;
}

sub parse_args {
  my @ary;
  foreach( @_ ) {
    my %hash;
    if (ref $_) {
      $hash{type} = ref $_;
    } else {
      $hash{type} = 'SCALAR';
    }
    $hash{value} = $_;
    push @ary, \%hash;
  }
  return \@ary;
}

Results:

[
    {
        "value": "test",
        "type": "SCALAR"
    },
    {
        "value": {
            "foo": "bar"
        },
        "type": "HASH"
    },
    {
        "value": [
            "one",
            "two",
            "three"
        ],
        "type": "ARRAY"
    }
]

Aggregates, Subroutines, and Command-Line Arguments, A command line argument is anything you type on the command line after the qw(Can unlock secret); my @second = qw(you the code?); my @mixed Yes, Perl does know that, but when we pass an array to a subroutine, It also becomes more difficult to handle the cases where one or more arguments are optional. Generic subroutine for various types of input arguments. I have a subroutine that receives a vector and rearranges its elements according to "mapping" vector. So for example the 1st element becomes 3rd, etc. This is done on integer, double, and double complex vectors.

Passing Arguments by Position and by Name, You cannot pass arguments by name to avoid entering required arguments. You can omit only the optional arguments. If the optional parameter is a reference type such as a String, you can use Nothing as the default value, provided this is not an expected value for the argument. Optional Parameters and Overloading. Another way to define a procedure with optional parameters is to use overloading.

[Chapter 2] 2.7 Subroutines, You can even call a subroutine indirectly using a variable containing either its name To declare and define a subroutine, use one of these forms: This is one of the ways where Perl's simple argument-passing style shines. It turns out that you can actually mix the typeglob approach with the reference approach, like this:. The order in which we pass arguments to the subroutine makes no difference; their names tell us where they are. And, if we want to leave out an optional argument when calling the subroutine, we can tell that from within the subroutine by testing for the existence of the hash element with the argument's name.

Optional Arguments with VBScript, What you can do is pass null values to your functions. for creating subroutines with optional arguments, consider the following example: where Subroutine_Name is the name of the subroutine and argument1 through argumentn are optional arguments, often called parameters, that you can pass to the subroutine. If you choose not to pass any arguments to the subroutine, the parentheses are optional, as you will see in a moment.

Comments
  • General advice: Always use strict;. Don't call your variables $a or $b (they have a special meaning in sort). Don't call subroutines with &.
  • Not an exact duplicate, but similar: stackoverflow.com/questions/8481405/…
  • thanks Melpomene. I have updated the code as per your suggestion. Since it's a just sample code so i didn't care about strict function.
  • Since it's a just sample code so i didn't care about strict function That's never a good idea :-)
  • Thanks Dave. I was looking a way to pass the optional arguments with hashes using perl subroutine. I got it working and here, is my sample code
  • Thanks Dave. I was looking a way to pass the optional arguments with hashes using perl subroutine. I got it working and here, is my sample code
  • So you've learned that a) optional arguments go at the end of the parameter list and b) it's better to pass hashes and arrays to subroutines as references.