This extra check halves the speed of Dictionary>>= when they are equal, for
all cases which consider equivalence symmetrical.  If a=b, then it should
be able to be assumed that b=a.  What case is it not?

On Mon, Oct 12, 2015 at 7:02 PM, <commits at source.squeak.org> wrote:

> Levente Uzonyi uploaded a new version of Collections to project The Trunk:
> http://source.squeak.org/trunk/Collections-ul.668.mcz
>
> ==================== Summary ====================
>
> Name: Collections-ul.668
> Author: ul
> Time: 13 October 2015, 1:07:48.216 am
> UUID: 8abfa05a-70c6-4e38-bc00-7d665183106c
> Ancestors: Collections-ul.667
>
> In Dictionary >> #=, make sure that the dictionaries agree on what the
> common keys are. This way the behaviour of #= will be symmetric when the
> two dictionaries implement key equality differently.
>
> =============== Diff against Collections-ul.667 ===============
>
> Item was changed:
>   ----- Method: Dictionary>>= (in category 'comparing') -----
> + = anObject
> - = aDictionary
>         "Two dictionaries are equal if
>          (a) they are the same 'kind' of thing.
>          (b) they have the same set of keys.
>          (c) for each (common) key, they have the same value"
>
> +       self == anObject ifTrue: [ ^true ].
> +       anObject isDictionary ifFalse: [ ^false ].
> +       self size = anObject size ifFalse: [ ^false ].
> +       self associationsDo: [ :association |
> +               (anObject at: association key ifAbsent: [ ^false ]) =
> association value
> +                       ifFalse: [ ^false ] ].
> +       "The two dictionaries may have different ideas about equal keys,
> so check both ways to avoid any inconsistency."
> +       anObject associationsDo: [ :association |
> +               (self at: association key ifAbsent: [ ^false ]) =
> association value
> +                       ifFalse:  [ ^false ] ].
> +       ^true!
> -       self == aDictionary ifTrue: [ ^ true ].
> -       aDictionary isDictionary ifFalse: [^false].
> -       self size = aDictionary size ifFalse: [^false].
> -       self associationsDo: [:assoc|
> -               (aDictionary at: assoc key ifAbsent: [^false]) = assoc
> value
> -                       ifFalse: [^false]].
> -       ^true
> -
> - !
>
>
>
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