Why does a list context shift on an empty array return (undef) ?

Shouldn't shift behave like one element splice

  DB<16> @array =()

  DB<17> (@x) = splice @array,0,1

  DB<18> x @x
  empty array
  DB<19> (@x) = shift @array

  DB<20> x @x
0  undef                                   # WTF

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update motivation

please note how loops over shift can't handle false values in scalar context, but become endless in list context.

This behaviour breaks conventions of other iterators ...

  DB<1> @x = (1..3,0,undef,1..3)

  DB<2> $max=100

  DB<3> while (my ($x) = shift @x) { print "$x,"; last if $max-- < 0 }
1,2,3,0,,1,2,3,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
+,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
  DB<4> @x = (1..3,0,undef,1..3)

  DB<5> while (my $x = shift @x) { print "$x," }
1,2,3,

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

In reply to shift on empty array in list context broken by LanX

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