Re: Can't understand one line

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( ... ) {
            ...
[download]

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(@_) );
[download]

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 >
[download]

Hope that helps,

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

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Re^2: Can't understand one line by anaconda_wly (Scribe) on Jan 07, 2013 at 08:44 UTC
That' great!Thanks!	[reply]

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