Hi Christoph,

On Sat, Mar 7, 2020 at 6:01 AM Thiede, Christoph <
Christoph.Thiede at student.hpi.uni-potsdam.de> wrote:

> Take this as a memo for myself -- of course, it would be great to hear
> your ideas about the following points!
>
>
> Further steps:
>
>
>
>    - Implement the same return logic for #while(True|False)[:]. This
>    might also require changes in the Compiler.
>    - Inline #whileNil(:) implementation as well.
>    General question: Is there such a thing as "too much inlining"? Would
>    it be desirable to inline #cull: and others? Where do we draw the line
>    between performance and Smalltalk-essential explorability?
>    - Implement all these controlling methods in a way that could work
>    without inlining (though slow). At the moment, #whileTrue: refers to itself.
>    An approach that completely foregos inline code would either need to
>    use recursion (linear complexity) or "thisContext restart" (constant
>    time complexity).
>    - Should we maybe find a way to highlight methods that are inlined?
>    For example, by using a pragma <inlined>. Or rather ask Encoder for it than
>    storing this information in the methods.
>    Should we warn or forbid the user to override (or even overwrite) such
>    methods?
>       - Similar concern: It is dangerous to override #class et al.,
>       should we warn here, too?
>
>
BTW, this is a hack, I would argue one that is extremely confusing for the
beginner:

whileTrue: aBlock
"Ordinarily compiled in-line, and therefore not overridable.
This is in case the message is sent to other than a literal block.
Evaluate the argument, aBlock, as long as the value of the receiver is
true."

^ [self value] whileTrue: [aBlock value]

It should read something like

whileTrue: aBlock
"Ordinarily compiled in-line, and therefore not overridable, and not
recursive.
This method exists in case the message is sent to other than a literal
block.
Evaluate the argument, aBlock, as long as the value of the receiver is
true."

self value ifTrue:
[aBlock value.
^self whileTrue: aBlock].
^nil

or

whileTrue: aBlock
"Ordinarily compiled in-line, and therefore not overridable, and not
recursive.
This method will be used if the message is sent to other than a literal
block.
Evaluate the argument, aBlock, as long as the value of the receiver is
true."

self value ifTrue:
[aBlock value.
 [self value] whileTrue: aBlock].
^nil

this is what it read in Smalltalk-80 v2:

whileTrue: aBlock
       "Evaluate the argument, aBlock, as long as the value
       of the receiver is true. Ordinarily compiled in-line.
       But could also be done in Smalltalk as follows"

       ^self value
               ifTrue:
                       [aBlock value.
                       self whileTrue: aBlock]

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:* Dienstag, 3. März 2020 22:38 Uhr
> *An:* squeak-dev at lists.squeakfoundation.org;
> packages at lists.squeakfoundation.org
> *Betreff:* [squeak-dev] The Trunk: Kernel-ct.1295.mcz
>
> Nicolas Cellier uploaded a new version of Kernel to project The Trunk:
> http://source.squeak.org/trunk/Kernel-ct.1295.mcz
>
> ==================== Summary ====================
>
> Name: Kernel-ct.1295
> Author: ct
> Time: 24 January 2020, 5:20:51.814415 pm
> UUID: 18ea3b5d-ee42-2944-9d01-aa48e43207a7
> Ancestors: Kernel-nice.1292
>
> Extends BlockClosure >> #whileNil: by returning the final non-nil value.
> Adds #whileNil analogous to #whileTrue and #whileFalse.
>
>         [Project uiManager chooseFrom: #(foo bar) values: #(Foo Bar)]
> whileNil.
>
>         [Project uiManager chooseFrom: #(foo bar) values: #(Foo Bar)]
> whileNil: [self inform: 'You have to decide!']
>
> =============== Diff against Kernel-nice.1292 ===============
>
> Item was added:
> + ----- Method: BlockClosure>>whileNil (in category 'controlling') -----
> + whileNil
> +        "Unlike #whileTrue/False this is not compiled inline."
> +        | result |
> +        [(result := self value) isNil] whileTrue.
> +        ^ result
> +        !
>
> Item was changed:
>   ----- Method: BlockClosure>>whileNil: (in category 'controlling') -----
>   whileNil: aBlock
>          "Unlike #whileTrue/False: this is not compiled inline."
> +        | result |
> +        [(result := self value) isNil] whileTrue: [aBlock value].
> +        ^ result
> -        ^ [self value isNil] whileTrue: [aBlock value]
>          !
>
>
>
>

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