[squeak-dev] #doWhileTrue: (was: The Trunk: System-nice.1149.mcz)

Eliot Miranda eliot.miranda at gmail.com
Wed Apr 1 00:26:49 UTC 2020


Hi Christoph,

On Mon, Mar 30, 2020 at 10:58 AM Thiede, Christoph <
Christoph.Thiede at student.hpi.uni-potsdam.de> wrote:

> Hi Nicolas,
>
>
> > There is no other sender of doWhileFalse: doWhileTrue: and my advice
> would be to deprecate them. YAGNI.
>
> So my image actually contains around two dozen senders of #doWhileTrue:
> and #doWhileFalse: (Squot, Pheno and some of my own code). As mentioned
> somewhere else in the past, I actually like them and find them very useful.
>
> In my opinion, many senders of #whileTrue and #whileFalse should be
> refactored to use #doWhileTrue:/#doWhileFalse:. Here is a random example:
>
> [newPlace := self getNewPlace.
> dir := ServerFile new fullPath: newPlace.
> (dir includesKey: dir fileName)] whileTrue.
>
> I find that's ugly and counter-intuitive! I would rewrite this in the
> following way:
>
> [newPlace := self getNewPlace.
> dir := ServerFile new fullPath: newPlace]
>     doWhileTrue: [dir includesKey: dir fileName].
>

Ugh, horrible.  The whileTrue is Smalltalk.  doWhilerye: is some kind of
attempt to do C.  I have to say that I *hate* diWhileTrue:.  whileTrue is
beautifully elegant.  You'll find it natural if you try and leave behind
the damage from more conventional control-flow ischemes.



>
> The latter just reads easier. blockReturns in multi-statement blocks are
> not really intuitive.
> In the first version, when scanning the method quickly, I read "okay,
> something with places and directories is done, while true ...," I wonder
> "what has to be true?" and have to look back to the end of the block and
> find the beginning of the last statement.
> But in the second version, I read "okay, something with places and
> directories is done, while that directory matches this specific condition."
> This version directly draws my attention to the important condition.
>
> Happy to hear your counterarguments :-)
>

Two blocks where one will do?  Unnecessary.  Blocks are objects and
understand messages, so whileTrue is coherent with the rest of the system,
more concise, and indeed to my eyes much more elegant.


>
> Best,
> Christoph
>
> ------------------------------
> *Von:* Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
> Auftrag von commits at source.squeak.org <commits at source.squeak.org>
> *Gesendet:* Montag, 30. März 2020 12:51 Uhr
> *An:* squeak-dev at lists.squeakfoundation.org;
> packages at lists.squeakfoundation.org
> *Betreff:* [squeak-dev] The Trunk: System-nice.1149.mcz
>
> Nicolas Cellier uploaded a new version of System to project The Trunk:
> http://source.squeak.org/trunk/System-nice.1149.mcz
>
> ==================== Summary ====================
>
> Name: System-nice.1149
> Author: nice
> Time: 30 March 2020, 12:50:26.196366 pm
> UUID: ece53b0b-24d2-4d4b-bc91-6794a661f886
> Ancestors: System-ul.1148
>
> avoid neuron storming [...] doWhileTrue: true, it just means [...] repeat
>
> There is no other sender of doWhileFalse: doWhileTrue: and my advice would
> be to deprecate them. YAGNI.
>
> =============== Diff against System-ul.1148 ===============
>
> Item was changed:
>   ----- Method: MOFile>>searchByHash: (in category 'experimental') -----
>   searchByHash: aString
>          | hashValue nstr index incr key |
>          hashValue :=  self hashPjw: aString.
>          incr := 1 + (hashValue \\ (hashTableSize -2)).
>          index := (hashValue \\ hashTableSize) .
>          [        nstr := (hashTable at: index +1 ).
>                  nstr = 0 ifTrue: [^nil].
>                  key := self originalString: nstr.
>                  key = aString ifTrue: [^self translatedString: nstr].
>                  index >= (hashTableSize - incr)
>                                  ifTrue: [index := index - (hashTableSize
> - incr)  ]
>                                  ifFalse:[index := index + incr].
> +        ] repeat!
> -        ] doWhileTrue: true.!
>
>
>
>

-- 
_,,,^..^,,,_
best, Eliot
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