--- Begin Message ---
This is cool. Rails has this kind of capability and I miss it elsewhere.
> On Dec 9, 2019, at 6:08 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
> <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
>
--- End Message ---
