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Re^4: Not understanding 2 sentences in perldoc

by Anonymous Monk
on Jul 29, 2020 at 20:52 UTC ( #11120018=note: print w/replies, xml ) Need Help??


in reply to Re^3: Not understanding 2 sentences in perldoc
in thread Not understanding 2 sentences in perldoc

haukex posted "The assignment my ($x, $y, $z) = qw( 1 2 3 ) happens first, i.e. those three variables are assigned the numbers 1 to 3, and this first assignment returns the lvalues, to which the values qw( a b c ) are immediately assigned."

"and this first assignment returns the lvalues" What lvalues does it return? I see (my ($x, $y, $z) = qw( 1 2 3 )) = qw( a b c ); as # 1 = 'a', 2 = 'b', 3 = 'c'.

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Re^5: Not understanding 2 sentences in perldoc
by LanX (Cardinal) on Jul 29, 2020 at 21:26 UTC
    • ( ... ) = is a list assignment with list context inside the parens

      we have two nested list assignments here

    •  my ($x, $y, $z) = qw( 1 2 3 ) is a list assignment

      effect $x=1, $y=2, $z=3

      returns lvalues $x, $y, $z in list context

    • ( $x, $y, $z ) = qw( a b c ); is a list assignment

      effect $x="a", $y="b", $z ="c"

      doesn't return because in void context (start statement)

    Hints

    • If you don't believe it please try it out
    • for terminology refer to perlglossary

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery

      Hi, it's me the anonymous monk.

      ( $x, $y, $z ) = qw( a b c );

      Why the above returns void context?

      (my ($x, $y, $z) = qw( 1 2 3 )) = qw( a b c );

      Does it return void context in this expression too?

Re^5: Not understanding 2 sentences in perldoc
by haukex (Bishop) on Jul 29, 2020 at 20:54 UTC
    What lvalues does it return?

    LanX answered that already here.

Re^2: Not understanding 2 sentences in perldoc
by perlfan (Vicar) on Jul 29, 2020 at 21:02 UTC
    This:
    (my ($x, $y, $z) = qw( 1 2 3 )) = qw( a b c );
    Is semantically equivalent to this,
    my ($x, $y, $z) = qw( 1 2 3 ); # $x = '1', $y = '2', $z = '3'. ($x, $y, $z) = qw( a b c ); # $x = 'a', $y = 'b', $z = 'c'.

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