RE: [MO-java-dev] Is IsEqual testing for equality in the right order?

[Tim M. <tim...@po...>]

There is a subtle difference when testing - sometimes you want to be able to
pass in an object (a mock version - where if there was no interface it
should still act as equal).

This implies that it is preferable to write equals as

equals(obj o) {
 return o.equals(this);
}

I  don't think we have this issue in the dynamic version and as nat points
out the constraints are written to handle this - but the older version did
have this issue sometimes...

Ignore this if its confusing - its just something that I remember from years
ago.


Tim
> -----Original Message-----
> From: moc...@li...
> [mailto:moc...@li...]On Behalf Of
> Nat Pryce
> Sent: 02 June 2003 23:09
> To: Vincent Tence; 'Mockobjects-Java-Dev'
> Subject: Re: [MO-java-dev] Is IsEqual testing for equality in the right
> order?
>
>
> > According to the Java equals protocol, the expressions
> arg.equals(_object)
> > and _object.equals(arg) must act the same, so it makes no
> difference.  If
> > the two expressions act differently, then that is a bug in the
> > implementation of the class of arg or _object.
>
> I should have also said: if you want different behaviour, you can always
> write a new constraint by implementing the Constraint interface.  This is
> exactly the situation that the Constraint interface was designed for.
>
> Cheers,
>             Nat.
>
> _______________________
> Dr. Nathaniel Pryce
> B13media Ltd.
> http://www.b13media.com
> +44 (0)7712 526 661
>
>
> ----- Original Message -----
> From: "Nat Pryce" <nat...@b1...>
> To: "Vincent Tence" <Vin...@ge...>; "'Mockobjects-Java-Dev'"
> <moc...@li...>
> Sent: Monday, June 02, 2003 11:07 PM
> Subject: Re: [MO-java-dev] Is IsEqual testing for equality in the right
> order?
>
>
> >
> > Cheers,
> >             Nat.
> > _______________________
> > Dr. Nathaniel Pryce
> > B13media Ltd.
> > http://www.b13media.com
> > +44 (0)7712 526 661
> >
> > ----- Original Message -----
> > From: "Vincent Tence" <Vin...@ge...>
> > To: "'Mockobjects-Java-Dev'"
> <moc...@li...>
> > Sent: Monday, June 02, 2003 10:57 PM
> > Subject: [MO-java-dev] Is IsEqual testing for equality in the
> right order?
> >
> >
> > > Hi,
> > >
> > > I noticed that the IsEqual constraint tests for equality by comparing
> the
> > > expected value against the actual value. IIRC it used to be the other
> way
> > > around with "static" mocks - i.e. expected.equals(actual) -
> so you could
> > > deal with legacy code not implementing equals correctly. It has helped
> me
> > in
> > > a number of situtations. Any reason why this has changed?
> > >
> > > Extract from IsEqual :
> > >
> > >     public boolean eval( Object arg ) {
> > >     if(arg instanceof Object[]) {
> > >     arg = Arrays.asList((Object[])arg);
> > >     }
> > >         return arg.equals(_object);
> > >     }
> > >
> > > It could be _object.equals(arg) or am I missing something?
> > >
> > > Thanks,
> > > Vincent
> > >
> > >
> > >
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>
>
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