Boolean expressions (was: Re: [squeak-dev] Re: Object>>#is:?
(was: Re: PackageDependencyTest))
leves at elte.hu
Thu Mar 4 21:50:50 UTC 2010
On Thu, 4 Mar 2010, Bert Freudenberg wrote:
> On 04.03.2010, at 22:21, Stéphane Rollandin wrote:
>>> If you have a lot of protocols you can use the super fast
>>> primitive supported #pointsTo: and have a lot cleaner (and possibly
>>> faster) code:
>>> is: aSymbol
>>> ^#(Morph MySpecializedMorph FooMorph BarMorph) pointsTo: aSymbol
>> wow. thanks for the pointer, I wasn't aware of this one :)
> It's also less readable. If you replace #pointsTo: with #includes: I know right away what it means. If you use this low-level optimization I have to think twice which object points where.
#includes: is a lot slower of course, that's why #pointsTo: is used in
MethodDictionary >> #includesKey:. We also have #identityIncludes: which
is not so fast, but could be overridden in SequenceableCollection for
In Cuis #is: could be implemented only in Object as something like
"#pointsTo: is used here for better performance"
^self implementedProtocols pointsTo: aSymbol
and #implementedProtocols could just return a literal Array, though it's
has an extra message send.
> - Bert -
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