Wait now I am confused...
I thought the whole spectacle is about hooking into the iterator on the arrays level.
But you are talking about the lvalue character on the elements level...
Probably I need to start reading the whole thread again ...
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use strict;
use warnings;
package MyClass;
use Tie::Array;
our @ISA = ('Tie::Array');
our @data;
# mandatory methods
sub TIEARRAY { my $class = shift; bless \@data, $class; @data = @_
+; return \@data }
sub FETCH { my ($self, $index ) = @_; print "FETCH($index)\n"; ret
+urn $data[$index] }
sub STORE { my ($self, $index, $value) = @_; print "STORE($index)\
+n"; $data[$index] = $value }
sub FETCHSIZE { print "<FETCHSIZE> "; return scalar @data }
package main;
my @x;
tie @x, "MyClass", 0, 0, 0;
my $x = \$x[2];
$$x++;
print "@x\n";
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[d/l]
[select] |
I'm not good with tie, but thought I'd take this as a learning exercise. I was surprised by using our @data instead of a fresh anonymous aref for each instance, so I tied @y to the same class to confirm it (confirmed). I wanted to untie those variables and re-use them to tie to a second class that used separate data structures in TIEARRAY (in spoiler; the mods worked as I expected, with separate data structures for @x and @y)... but was surprised at the "untie attempted while 2 inner references still exist" warning when I did the untie. I thought the $x reference was probably the culprit, so undefined that.... but there was still one remaining inner reference. What is the second inner reference, and where did it come from?
use strict;
use warnings;
package MyClass; {
use Tie::Array;
our @ISA = ('Tie::Array');
our @data;
#mandatory methods
sub TIEARRAY { my $class = shift; bless \@data, $class; @data = @_
+; return \@data }
sub FETCH { my ($self, $index ) = @_; print "FETCH($index)\n"; ret
+urn $data[$index] }
sub STORE { my ($self, $index, $value) = @_; print "STORE($index)\
+n"; $data[$index] = $value }
sub FETCHSIZE { print "<FETCHSIZE> "; return scalar @data }
};
package main;
$|++;
local $" = ", ";
my @x;
tie @x, "MyClass", 0, 0, 0;
my $x = \$x[2];
$$x++;
print "x = (@x)\n";
=begin comment
When I first saw the above, it looked like no matter how many items we
+re tied, they would all refer to the same @MyClass::data internal arr
+ay.
The next few lines showed that's true: when I tied @y to the same clas
+s, @x lost its data; and when an element of @y was changed, the same
+happened to @x.
=cut
my @y;
tie @y, "MyClass", 0, 0, 0;
print "y = (@y)\n";
print "x = (@x)\n";
$y[1] = 3.14;
print "y = (@y)\n";
print "x = (@x)\n";
untie @y; # gives a warning: untie attempted while 2 inner refer
+ences still exist
undef $x; # uncomment to reduce next warning to 1 instead of 2;
+comment to keep next warning at 2
untie @x; # warning, but with only 1 warning if previous line un
+commented
print "y = (@y)\n";
print "x = (@x)\n";
# so what's the second inner reference?
=begin comment
When I first saw the above, it looked like no matter how many items we
+re tied, they would all refer to the same @MyClass::data internal arr
+ay.
The next few lines showed that's true: when I tied @y to the same clas
+s, @x lost its data; and when an element of @y was changed, the same
+happened to @x.
=cut
my @y;
tie @y, "MyClass", 0, 0, 0;
print "y = (@y)\n";
print "x = (@x)\n";
$y[1] = 3.14;
print "y = (@y)\n";
print "x = (@x)\n";
untie @y; # gives a warning: untie attempted while 2 inner refer
+ences still exist
undef $x; # uncomment to reduce next warning to 1 instead of 2
untie @x; # warning, but with only 1 warning if previous line un
+commented
print "y = (@y)\n";
print "x = (@x)\n";
# so what's the second inner reference?
=begin comment
I wanted to see if I understood enough: make a replica, but use a new
+anonymous array, rather than having an @data;
MySecond properly keeps @x and @y from interacting.
=cut
package MySecond; {
use Tie::Array;
our @ISA = ('Tie::Array');
#mandatory methods
sub TIEARRAY { my $class = shift; my $self = bless [], $class; @$s
+elf = @_; return $self }
sub FETCH { my ($self, $index ) = @_; print "FETCH($index)\n"; ret
+urn $self->[$index] }
sub STORE { my ($self, $index, $value) = @_; print "STORE($index)\
+n"; $self->[$index] = $value }
sub FETCHSIZE { my ($self) = @_; print "<FETCHSIZE> "; return scal
+ar @$self }
};
tie @x, "MySecond", 0, 0, 0;
tie @y, "MySecond", 0, 0, 0;
$x[1] = 2.718;
$y[0] = 0.000281828;
print "|| x = (@x)\n";
print "|| y = (@y)\n";
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[d/l]
[select] |
| [reply] |
