in reply to Using 'Shift' in subroutine argument

perldoc -f shift tells us: 
    shift ARRAY
    shift   Shifts the first value of the array off and returns it,
            shortening the array by 1 and moving everything down. If t
+here
            are no elements in the array, returns the undefined value.
+ If
            ARRAY is omitted, shifts the @_ array within the lexical s
+cope
            of subroutines and formats, and the @ARGV array at file sc
+opes
            or within the lexical scopes established by the "eval ''",
            "BEGIN {}", "INIT {}", "CHECK {}", and "END {}" constructs
+.

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In this case, it's likely that it's being used within another subroutine, so it's shifting the @_ array.

-- Randal L. Schwartz, Perl hacker

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Re^2: Using 'Shift' in subroutine argument
by narainhere (Monk) on Nov 02, 2007 at 11:31 UTC
    If you execute this 
    use strict;
use warnings;
one(1,2,3,4);
sub one{
    &two (shift, shift);
}
sub two
{
    print "Elements : \n @_ \n";
}

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    you would get 
    Elements :
 1 2

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    Which means that it's same as passing the first two elements of the list the sub-routine one has received.Though I was not able to compile the code 
    sub one{
    &two shift, shift;
}

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    which is your case.Provide the some context of your snippet that would help everyone to learn.

    The world is so big for any individual to conquer

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      Though I was not able to compile the code 
      sub one{
    &two shift, shift;
}

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      That's a syntax error. Subroutine invocations with & require parens.

      Drop the ampersand and move the sub two definition up: 

      use strict;
use warnings;
one(1,2,3,4);
sub two {
    print "Elements : \n @_ \n";
}
sub one {
    two shift, shift;
}

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      To resolve the bareword two as a subroutine call (in two shift, shift), the compiler needs to have seen the sub declaration already. Alternative: 

      use strict;
use warnings;
sub two;      # forward declaration
one(1,2,3,4);
sub one {
    two shift, shift;
}
sub two {
    print "Elements : \n @_ \n";
}

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      --shmem 

      _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
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