[squeak-dev] The Inbox: Collections-pre.838.mcz

Marcel Taeumel marcel.taeumel at hpi.de
Tue Jul 2 06:58:10 UTC 2019

...and if you avoid looking at the implementation of #do: and #associationsDo:? The term "associations" leaks some internal representation detail. :-)

Am 01.07.2019 21:29:20 schrieb Chris Muller <asqueaker at gmail.com>:

Hi, there.

>From the client's perspective, isn't #do: already an abstraction level higher than #assocationsDo:?

Not when one accounts for the receiver.  

    order do: [ ... ]

has to make assumptions about the internal representation, and it duplicates the responsibility for enumerating the receiver just to do some broader function (printing elements), even though the receiver already has a method to do that enumeration.

   self associationsDo: [ ... ]


It is so on the implementation side, too - at least in Collection. Swapped in Dictionary and OrderedDictionary, though.


Collection >> associationsDo: aBlock
"Evaluate aBlock for each of the receiver's elements (key/value 
associations).  If any non-association is within, the error is not caught now,
but later, when a key or value message is sent to it."

self do: aBlock

Dictionary >> associationsDo: aBlock 
"Evaluate aBlock for each of the receiver's elements (key/value 

tally = 0 ifTrue: [ ^self].
1 to: array size do: [ :index |
(array at: index) ifNotNil: [ :element |
aBlock value: element ] ]

OrderedDictionary >> associationsDo: aBlock
"Iterate over the order instead of the internal array."

order from: 1 to: tally do: aBlock

Am 01.07.2019 02:47:26 schrieb Chris Muller <asqueaker at gmail.com [mailto:asqueaker at gmail.com]>:
Hi Patrick,

Would you be willing to employ the highest-level methods possible?   "order do: [ .... ", creates an unnecessary dependency on the implementation when it appears #associationsDo: would work fine..?

It looks like it would put a space before the last paren.  Picky, I know, but there is #do:separatedBy: to the rescue.  I guess you could pre-allocate the OrderedDictionary to the proper size.

For the RunArray, could #runsAndValuesDo: help here?  I'm having trouble following this code.  At least in core code, #at:ifAbsentPut: should take a block for the second argument, IMO.


On Fri, Jun 28, 2019 at 5:11 AM <commits at source.squeak.org [mailto:commits at source.squeak.org]> wrote:

Patrick Rein uploaded a new version of Collections to project The Inbox:
http://source.squeak.org/inbox/Collections-pre.838.mcz [http://source.squeak.org/inbox/Collections-pre.838.mcz]

==================== Summary ====================

Name: Collections-pre.838
Author: pre
Time: 28 June 2019, 12:11:16.302033 pm
UUID: db29f1b2-09b5-f045-aa21-9379185664df
Ancestors: Collections-pre.837

Two method additions to Collection. The first adds ordered printing to OrderedDictionaries, to allow users to actually see the ordering. The second adds a method to convert a run array into an expanded version of the runs.

=============== Diff against Collections-pre.837 ===============

Item was added:
+ ----- Method: OrderedDictionary>>printElementsOn: (in category 'printing') -----
+ printElementsOn: aStream
+       "Based on Dictionary>>#printElementsOn:"
+       aStream nextPut: $(.
+       self size > 100
+               ifTrue: [aStream nextPutAll: 'size '.
+                       self size printOn: aStream]
+               ifFalse: [order do: [:assoc | assoc ifNotNil: [
+                                       assoc printOn: aStream. aStream space]]].
+       aStream nextPut: $)!

Item was added:
+ ----- Method: RunArray>>asValuesAndIntervals (in category 'converting') -----
+ asValuesAndIntervals
+       | interval result |
+       result := OrderedDictionary new.
+       1 to: self size do: [:i |
+               (self at: i) do: [:value |
+                       interval := result at: value ifAbsentPut: (i to: i).
+                       result at: value put: (interval start to: i)]].
+       ^ result
+       !

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