Re: [rules-dev] BUG: [5.3.0.Final] CollectSetAccumulateFunction should probably use IdentityHashMap internally
By the way, while checking into various scenarios prompted by Wolfgang's
response, I came up with a very interesting test program:
rule "Initialize"
salience 100
when
eval(true)
then
insert("one");
insert(new String("one"));
insertLogical("two");
insertLogical(new String("two"));
end
rule "Find strings"
salience 50
when
$s : String()
then
System.out.println("I found string: " + $s);
end
rule "Gather strings"
salience 50
when
accumulate(
$s : String(),
$sSet : collectSet( $s ),
$sList : collectList( $s ) )
then
System.out.println("Here is the set of all strings: " + $sSet);
System.out.println("Here is the list of all strings: " + $sList);
end
What would you expect that to output? How many "I found string: xxx" lines
would there be? How many entries in the "set of all strings"? How many
entries in the "list of all strings"?
For my part, I figured there would be four "I found string: xxx" lines, two
entries in the set, and four entries in the list.
I was very surprised to find the following output:
I found string: two
I found string: one
I found string: one
Here is the set of all strings: [two, one]
Here is the list of all strings: [one, one, two]
This strongly suggests that "insert" objects are held in an
identity-preserving structure, but that "insertLogical" objects are held in
an equals()-based structure.
I am glad for the identity-based handling of "insert" objects, especially
considering that all of my inserted objects come from "outside" the engine.
I would hate to see one of them fail to be considered by the rule engine.
I can almost see some usefulness for the equals() behavior of insertLogical
objects, but far more potential problems.
I think it's slightly dangerous that these behaviors differ and that it is
not, AFAIK, documented in a way that is clear to users of Drools.
--
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