Hi Julien,

Interesting, in the last years I've been using a similar set of
classes that build groups, and can also nest them, but yours seems
more customizable.

Thank you for sharing it.

I'll give it a try!


Esteban A. Maringolo


On Mon, Dec 9, 2019 at 11:10 AM Julien Delplanque
<[email protected]> wrote:
>
> Hello,
>
> I made a small library that reify grouping (that one does via #groupBy: 
> usually): Grouper https://github.com/juliendelplanque/Grouper
>
> It is designed in the same spirit as SortFunction, but for grouping.
>
> Quick example:
>
> The following code snippet using Grouper:
>
> (10 to: 50) groupUsing: [ :integer | integer asString first ].
> "an OrderedDictionary(
>   $1->#(10 11 12 13 14 15 16 17 18 19)
>   $2->#(20 21 22 23 24 25 26 27 28 29)
>   $3->#(30 31 32 33 34 35 36 37 38 39)
>   $4->#(40 41 42 43 44 45 46 47 48 49)
>   $5->#(50))"
>
> is equivalent to the following code snippet using built-in #groupedBy: method:
>
> (10 to: 50) groupedBy: [ :integer | integer asString first ]
> "an OrderedDictionary(
>   $1->#(10 11 12 13 14 15 16 17 18 19)
>   $2->#(20 21 22 23 24 25 26 27 28 29)
>   $3->#(30 31 32 33 34 35 36 37 38 39)
>   $4->#(40 41 42 43 44 45 46 47 48 49)
>   $5->#(50))"
>
> The advantage of using it is that it allows one to compose grouper objects.
>
> Thus, it is easy to describe grouping on 2 or 3 levels.
>
> Fore example:
>
> The power of Grouper is that group description are first-class objects. Thus, 
> it is possible to compose group descriptions in order to group a flat 
> collection on multiple levels.
>
> For example:
>
> groupComposition := [ :integer | integer asString first ] grouper , [ 
> :integer | integer asString second ].
> (10 to: 50) groupUsing: groupComposition.
> "an OrderedDictionary(
>   $1->an OrderedDictionary(
>     $0->#(10) $1->#(11) $2->#(12) $3->#(13) $4->#(14) $5->#(15) $6->#(16) 
> $7->#(17) $8->#(18) $9->#(19))
>   $2->an OrderedDictionary(
>     $0->#(20) $1->#(21) $2->#(22) $3->#(23) $4->#(24) $5->#(25) $6->#(26) 
> $7->#(27) $8->#(28) $9->#(29))
>   $3->an OrderedDictionary(
>     $0->#(30) $1->#(31) $2->#(32) $3->#(33) $4->#(34) $5->#(35) $6->#(36) 
> $7->#(37) $8->#(38) $9->#(39))
>   $4->an OrderedDictionary(
>     $0->#(40) $1->#(41) $2->#(42) $3->#(43) $4->#(44) $5->#(45) $6->#(46) 
> $7->#(47) $8->#(48) $9->#(49))
>   $5->an OrderedDictionary($0->#(50)))"
>
> On the github, there are more example showing how to build trees with custom 
> objects.
>
> Any feedback for this library is welcome.
>
> I would like to propose it to Pharo in the near future because it would 
> simplify a lot of code in DrTests (related to result tree views, the tree on 
> the right of the UI).
>
> I don't know if it will be possible before next release as we are in feature 
> freeze.
>
> Cheers,
>
> Julien

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