in reply to undef a List of Variables

It's easy to define a function that works like undef but allows multiple arguments. For example: 

sub undeff { @_[0..@_-1] = (); }; 
$foo = 5; $bar = 8; 
undeff($foo, $bar); # this undefs both of them
print "foo=[$foo] bar=[$bar]\n"; # prints `foo=[] bar=[]' and two warn
+ings

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Re^2: undef a List of Variables
by dragonchild (Archbishop) on Jan 31, 2005 at 17:31 UTC
    sub undeff { @_[0..-1] = (); };

    -1 is the last index ... much easier to read. (And faster, too.)

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[reply]
[d/l]

      Yes, that works in most other languages. In ruby, arr[0..-1] returns all elements of the array (and is an lvalue too). In python, arr[0:-1] is all but the last element, arr[0:] or arr[:] is all elements. In octave, you don't have negative array indexes, but you have avec(:) for all of the vector, but also no special notation for all the elements starting the n'th (like arr[n:] in python). In mathematica, you have arr[[All]] for all elements of the array, but also no starting slice notation. (These are only a few languages of course.)

      Anyway, you can write 0..$#_ or even 0..@_ as the index, or avoid indexing completely and say sub undeff { undef $_ for @_ }.

[reply]
[d/l]
[select]
      But it does not work.
      0..-1 is zero elements.
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