Re: Array/List Strangeness

Another two cases:

{
  my @b;
  my @a = @b[1,0]; 
  print Dumper(\@a);   # $VAR1 = [ undef, undef ]
}
{
  my @b;
  my @a = (@b)[0]; 
  print Dumper(\@a);   # $VAR1 = []
}
[download]

The first makes sure that it is not about slices vs. non-slices

The second shows that it really is about lists vs. arrays. And also that it is an inconsistency that matters in real code (unlike the academic example ()[0] )

The idiom is somewhat useful: my @a= (@b)[0..99]; would create a new array of max size 100, but won't make the new array larger if @b has fewer than 100 elements. And since there is probably code out there using this I don't think this inconsistency can be changed

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Re^2: Array/List Strangeness by LanX (Saint) on Aug 05, 2009 at 17:29 UTC
The idiom is somewhat useful: `my @a= (@b)[0..99];` would create a new array of max size 100, but won't make the new array larger if @b has fewer than 100 elements. And since there is probably code out there using this I don't think this inconsistency can be changed I don't know what you mean, can't see any general difference between slicing @b or (@b), except when $#b==0! `DB<38> @b=1..3 DB<39> x @b[0..6] 0 1 1 2 2 3 3 undef 4 undef 5 undef 6 undef DB<40> x (@b)[0..6] 0 1 1 2 2 3 3 undef 4 undef 5 undef 6 undef` [download] now 0-element array! `DB<43> @b=() DB<44> x @b[0..6] 0 undef 1 undef 2 undef 3 undef 4 undef 5 undef 6 undef DB<45> x (@b)[0..6] empty array` [download] Cheers Rolf	[reply] [d/l] [select]
Re^3: Array/List Strangeness by jethro (Monsignor) on Aug 05, 2009 at 20:26 UTC
Look at the time the node was posted, it was when I still had hope ;-) and no indication of further inconsistent behaviour	[reply]
Re^3: Array/List Strangeness (out-of-bounds) by tye (Sage) on Aug 05, 2009 at 18:48 UTC
You have to make all of the elements referenced out-of-bounds. Compare `@b[@b,1+@b]` vs `(@b)[@b,1+@b]` (whether @b is empty or not). - tye	[reply] [d/l] [select]