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Re^4: Not understanding 2 sentences in perldoc

by Anonymous Monk
on Jul 29, 2020 at 20:37 UTC ( #11120013=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

"($x, $y, $z) are after the first assignment ready for the next one." The next one is the assignment to qw( a b c ); ?

And what happens to qw( 1 2 3 ) in (my ($x, $y, $z) = qw( 1 2 3 )) = qw( a b c ); # $x = 'a', $y = 'b', $z = 'c'. ?

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Re^5: Not understanding 2 sentences in perldoc
by haukex (Bishop) on Jul 29, 2020 at 20:40 UTC

    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. Update: In other words, the numbers are assigned to the variables, but then immediately overwritten. Since this is just some example code it doesn't make much sense here, but in theory, you could for example be assigning to tied variables where assigning to the variable has some side effect, then it would make a difference.

      > it doesn't make much sense here,

      I'm often using it for setting defaults before unpacking @_ which could have 0,1 or 2 arguments

       ( my ($x,$y) = (42,666) ) = @_;

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

        I'm often using it for setting defaults before unpacking @_ which could have 0,1 or 2 arguments

        Sure, that makes sense ;-) With "it doesn't make much sense here" I meant the specific example with fixed values.

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