| Subject: | unclear documentation for Tree::AVL::acc_lookup() |
| Date: | Sat, 12 Nov 2011 16:37:14 -0500 (EST) |
| To: | bug-Tree-AVL [...] rt.cpan.org |
| From: | Jonathan Thornburg <jthorn [...] astro.indiana.edu> |
Hi,
I'm using your Tree::AVL perl module (version 1.075, downloaded from
cpan a day or two ago, with perl 5.12.2 on OpenBSD 5.0-release), and
I'm delighted with the functionality it provides. The purpose of this
message is to (a) thank you for providing such a *great* module, and
(b) point out what seems to me to be a documentation bug: the result
returned by acc_lookup() is different from what the documentation
describes.
In particular, the documentation states:
Show quoted text
> acc_lookup()
> my @found_things = $avltree->acc_lookup($thing, $partial_cmp_func, $p
> recise_cmp_func);
>
> Accumulative lookup; returns a list of all items whose keys satisfy the
> match function for the key for $object.
which to me says that acc_lookup() returns a list of (references to)
tree nodes (I presume that's what's mean by the word "items") satisfying
the partial-comparison equality criterion.
To see if I understood this properly, I wrote a simple test program
(attached, along with its output) which sets up a Tree::AVL of 3 nodes,
each (a reference to) an anonmous hash
{
_time => number
_modes => [list of numbers]
}
then uses acc_lookup() to look for all nodes with _time close to a
specified value, then uses Data::Dumper() to print the returned result
of acc_lookup() . The result is that acc_lookup() is returning a
list of the _time values, not a list of (references to) the nodes:
looking for nodes near time 41.9999999999
found 2 nodes:
$VAR1 = '42.0000000001';
$VAR2 = 42;
suggesting that the returned result was a 2-element list of the keys
(here 42+1e-10 and 42), rather than a 2-element list of references to
the tree nodes themselves (which would have had additional data printed).
Looking at the Tree::AVL source code (AVL.pm, lines 1040-1045), it also
seems to be accumulating a list of node keys:
Show quoted text> if($partial_cmp == 0){ # found a match on partial cmp
>
> if(!$acc_results){
> @$acc_results = ();
> }
> push(@$acc_results, $node_key);
I'm attaching 4 files:
* foo = a simple test program which creates 3 objects of a simple tree-node
class, inserts them into a Tree::AVL, and does an acc_lookup()
to find all those close to a certain key
* foo.out = the output of this program on my computer
* perl-V = the output of 'perl -V' on my computer
* uname-a = the output of 'uname -a' on my computer
thanks, ciao,
--
-- Jonathan Thornburg <jthorn@astro.indiana.edu>
Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA
"Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral."
-- quote by Freire / poster by Oxfam
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