On 17 Sep 2000, Perl6 RFC Librarian wrote:
> my $name = undef;
> my($a, $b, $c, $d, $e, $f) = undef;
Well, these two get the result they want. Try this code:
my($a, $b, $c, $d, $e, $f) = undef;
my %h = ( a => $a, b => $b, c => $c, d => $d, e => $e, f => $f );
while (my ($k, $v) = each %h)
{
print defined $v ? "$k is defined" : "$k is undefined";
print "\n";
}
it prints:
a is undefined
b is undefined
c is undefined
d is undefined
e is undefined
f is undefined
Why would anyone expect that assigning undef to anything would produce an
empty string. That makes no sense at all.
> my $name = empty;
what's wrong with $name = '';
> my($a, $b, $c, $d, $e, $f) = empty;
> my(@name, $age, %attrs) = empty;
What is the point of doing
my @name = ();
That's the same as:
my @name;
In fact, only for scalars does your proposed empty builtin do anything
different from my or local in terms of the value of the variable.
> And its purpose is intuitive: It causes a value to become C<empty>,
> without being undefined. Note that it can also shorten code in some
> situations.
Well, I don't want to encourage people to needlessly 'initialize'
variables in Perl.
The only case where it makes a difference is where you do:
my $x;
$x .= 'a';
$x .= 'b';
and you'll get an unitialized value warning. In that case, doing:
my $x = '';
is shorter and clearer. There's no point in trying to 'initialize' arrays
or hashes, because you'll never get those warnings with it.
> Nonetheless, feel free to point out why this is a bad idea and I'll
> gladly retract it.
See the above ;)
-dave
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