$registry->$_( shift(@_) )
^^^^^^^^^^^  ^           ^............invoke a method
           ^^             ............the name of which is stored in $
+_
              ^^^^^^^^^^  ............passing the next value from @_ a
+s an argument. 
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OK, but what is the sequence? "shift(@_) "first , or $_ first? in

$registry->$_( shift(@_) )
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I guess shift(@_) must be first, or else meaningless. Thanks!

... shift(@_) must be first ...

Quite right.

shift(@_) is a current $_

No. Here is the skeleton of the opening of the import subroutine in Win32::TieRegistry:

sub import
{
    my $pkg = shift(@_);
    ...
    local( $_ );
    while(  @_  ) {
    $_= shift(@_);
    if( ... ) {
            ...
    } elsif( ... ) {
            ...
            ...
    } elsif(  exists $_opt_subs{$_}  ) {
            ...
        $registry->$_( shift(@_) );
    } elsif( ... ) {
            ...
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Each call to shift removes another element from the head of the @_ array, i.e., another argument from the list of those passed into sub import. So in the line:

$registry->$_( shift(@_) );
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the variable $_ holds the last argument to have been removed from @_; but the expression shift(@_) removes the next argument from @_. $_ and shift(@_) will (most likely) have different values.

shift(@_) does not reset the value of $_:

17:43 >perl -wE "f(1, 2, 3); sub f { local($_) = shift(@_); my $c = sh
+ift(@_); say '$_ = ', $_; say '$c = ', $c; say '@_ = ', @_; }"
$_ = 1
$c = 2
@_ = 3

18:07 >
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Hope that helps,

That' great!Thanks!

They are totally separate variables.

use strict; 
use warnings; 
use 5.012;

package Person;
sub new
{
    my $class = shift;
    my $self = {};
    bless $self, $class;
    return $self;
}

sub do_this {
    my($self, $greetee) = @_;
    say "hello $greetee";
}

sub do_that {
    my($self, $greetee) = @_;
    say "goodbye $greetee";
}

1;
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use strict; 
use warnings; 
use 5.012;

use Person;

my $obj = Person->new;
$obj->do_this("Sam");
$obj->do_that("Cathy");

say '*' x 20;

my @func_names = ('do_this', 'do_that');
my @names = ("Sam", "Cathy");

call_funcs(@names);

sub call_funcs {
    for (@func_names) {
        $obj->$_(shift @_);
    }
}

--output:--
hello Sam
goodbye Cathy
********************
hello Sam
goodbye Cathy


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