VAST 8.5.2 - Set hash and equality are incompatible/incorrect

| s1 s2 ss |
s1 := Set with: #ActionButtonSpec.
s2 := Set with: #ActionButtonSpec.
ss := Set with: s1 with: s2.
Array
    with: ss size
    with: s1 = s2

This answers (2 true) when it should answer either (2 false) or (1 true). The latter is the preferred answer.

| s1 s2 ss |
s1 := Set with: #ActionButtonSpec.
s2 := Set with: #ActionButtonSpec.
ss := Set with: s1 with: s2.
Array
    with: ss size
    with: s1 = s2

This answers (2 true) when it should answer either (2 false) or (1 true). The latter is the preferred answer.

Thanks, John. Will this be the official fix in the next version?

On Tue, Sep 24, 2013 at 1:57 PM, John O'Keefe <<a href="javascript:" target="_blank" gdf-obfuscated-mailto="3cmF3WDAjtYJ">john_...@instantiations.com> wrote:

Richard -

The problem is that Set is missing an implementation of #hash. Try adding this method to Collection (you will then get (1 true)):

hash

"Synopsis

Return an integer hash code that can be used in conjunction with an #= comparison.

Definition: <Object>

An integer value that can be used as a hash code for the receiver is returned. The hash code is

intended for use in conjunction with an #= comparison.

The range, minimum, and maximum values of the result is implementation defined.

Any two objects that are considered equivalent using the #= message must have the same hash

value. More formally:

receiver = comparand iff

receiver hash = comparand hash

The hash value of an object need not be temporally invariant. Two independent invocations of

#hash with the same receiver may not always yield the same results. But note that collections

that use #= to discriminate objects may only reliably store objects whose hash values do not

change while the objects are contained in the collection.

Return Value

<integer>unspecified

Errors

none

Implementation Notes:

It would be more correct to include all elements of the receiver in the hash calculation, but we

don't want the calculation to take a significant length of time, so an arbitrary limit of 8

elements is used. If there are more than 8 elements, the hash gets pretty simple."

| hash |

hash := self species hash.

self size <= 8 ifTrue: [

hash := self inject: hash into: [ :ans :elem | ans bitXor: elem hash ] ].

^ hash bitXor: self size hash

John 

On Wednesday, September 11, 2013 6:24:02 PM UTC-4, Richard Sargent wrote:

| s1 s2 ss |
s1 := Set with: #ActionButtonSpec.
s2 := Set with: #ActionButtonSpec.
ss := Set with: s1 with: s2.
Array
    with: ss size
    with: s1 = s2

This answers (2 true) when it should answer either (2 false) or (1 true). The latter is the preferred answer.

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Richard Sargent Business Development Manager <a href="javascript:" target="_blank" gdf-obfuscated-mailto="3cmF3WDAjtYJ">richard...@gemtalksystems.com

GemTalk Systems 15220 NW Greenbrier Parkway #240 Beaverton, OR 97006

It looks like the problem is in the #with:with: method.  (Set with: s1) add: s2 works as expected.  If I was you, I'd report the #with:with: method as a bug according to the info on http://www.instantiations.com/support/index.html#contact .

All the with:with:...with: methods are a problem.  Inside those methods for the Set class it should not call "self new:" but  "self new".

On Wednesday, September 11, 2013 6:24:02 PM UTC-4, Richard Sargent wrote:

| s1 s2 ss |
s1 := Set with: #ActionButtonSpec.
s2 := Set with: #ActionButtonSpec.
ss := Set with: s1 with: s2.
Array
    with: ss size
    with: s1 = s2

This answers (2 true) when it should answer either (2 false) or (1 true). The latter is the preferred answer.

Richard -

Yes, unless I did it wrong :-)

John