On Wed, Dec 23, 2009 at 10:41 AM, <[email protected]> wrote:
> Em 23/12/2009 16:10, Eliot Miranda < [email protected] > escreveu:
>
> >
> > Core.SequenceableCollection comparing
> > isSameSequenceAs: otherCollection
> >
> > "Answer whether the receiver's size is the same as otherCollection's
> > size, and each of the receiver's elements equal the corresponding
> > element of otherCollection."
> >
> > | size |
> > (size := self size) = otherCollection size ifFalse: [^false].
> > 1 to: size do: [:index |
> > (self at: index) = (otherCollection at: index) ifFalse: [^false]].
> > ^true
> >
> > i.e. trust the caller is providing a sequence and if
> > otherCollection doesn't implement at: there will be a run-time
> > error, hence any otherCollection isKindOf: SequenceableCollection is
> > just wasted cycles.
> >
>
> I don't think that "trusting the caller" makes sense in this case, so
> I propose instead that you implementation be complemented by:
>
> Object>>isSameSequenceAs: otherCollection
> ^false
>
We're talking about the argument otherCollection not the receiver. i.e.
leaving out isKindOf: in
isSameSequenceAs: otherCollection
"Answer whether the receiver's size is the same as
otherCollection's size, and each
of the receiver's elements equal the corresponding element of
otherCollection."
| size |
(otherCollection isKindOf: SequenceableCollection) ifFalse:
[^false]. "this is a horrible wart"
(size := self size) = otherCollection size ifFalse: [^false].
1 to: size do: [:index |
(self at: index) = (otherCollection at: index) ifFalse:
[^false]].
^true
You could use double dispatching:
SequenceableCollection>>isSameSequenceAs: otherThing
^otherThing isSameSequenceAsSequence: self
SequenceableCollection>> isSameSequenceAsSequence: aSequenceableCollection
aSequenceableCollection size ~= self size ifTrue: [^false].
etc
Object isSameSequenceAsSequence: aSequenceableCollection
^false
but I think in this case it's overkill.
> --
> Cesar Rabak
>
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