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<p>Hi.</p>
<p>An interesting facet of eventual sending with promises is the
bonus of sending multiple result handlers to a single eventual
send result promise. So multiple result handlers, or whatever best
describes, for whatever that is worth.</p>
<p>Here are 3 return handlers, <br/>
</p>
<blockquote>
<p>promise := ((pair := self promiseResolverPair) key xgcd: 9).</p>
</blockquote>
<p>the first for each argument <br/>
</p>
<blockquote>
<p>promise <<* [:each | selectCount := selectCount + 1.
Transcript cr; show: 'each = ', each];</p>
</blockquote>
<p>and the last 2 for all three arguments.</p>
<blockquote>
<p>promise <<* [:g :s :t | firstUnionFlag := true.
Transcript cr; show: 'gcd = 'g'].</p>
<p>promise <<* [:g :s :t | secondUnionFlag := true.
Transcript cr; show: 'g = ', g, '; s = ', s, '; t = ', t.].</p>
</blockquote>
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<p></p>
<div class="moz-cite-prefix">On 6/23/23 16:15, Luciano
Notarfrancesco wrote:<br/>
</div>
<blockquote type="cite" cite="mid:CAL5GDyoz_kWja=LN_ods3VxmbsnAAqt9OgP0_AL8bXgpgbYC6A@mail.gmail.com">
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<div dir="auto">Right, good point! Fortunately, messages with
multiple return values are not very common in my system, I just
have a few examples, and I’ll rewrite them with Juan’s
suggestion, and I’ll keep your point in mind.</div>
<div><br/>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Fri, 23 Jun 2023 at 21:33
Nicolas Cellier <<a href="mailto:nicolas.cellier.aka.nice@gmail.com" moz-do-not-send="true" class="moz-txt-link-freetext">nicolas.cellier.aka.nice@gmail.com</a>>
wrote:<br/>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div dir="ltr">
<div>Hi all,</div>
<div>please note that the keyword message did eliminate
the positional semantics found in almost every other
language.</div>
<div>With multiple return arguments, as well as multiple
arguments block workaround, we are back to a kind of
positional semantic.</div>
<div>Of course, there is still some name used as block
args [:g :s :t | ...] but nothing would tell that [:t :g
:s | ...] is a mistake.</div>
<div>A hint on order can be given by the keyword used to
pass block argument, like qr: [:quo :rem | ] or
whatever, but when there is more than 2, naming is
getting difficult.</div>
</div>
<div dir="ltr">
<div>Nicolas<br/>
</div>
<div><br/>
</div>
</div>
<br/>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">Le ven. 23 juin 2023
à 21:00, rabbit via Cuis-dev <<a href="mailto:cuis-dev@lists.cuis.st" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">cuis-dev@lists.cuis.st</a>>
a écrit :<br/>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div>
<p>I just realized I have been working in squeak. I
updated PromisesLocal-rabbt.66.mcz and am attaching
it. I am getting the error below when I 'browse
code' or 'install Mionticello package'. I do not
know. How can I load Monticello packages? Any way to
get the Installer available in cuis? Install
Monticello config maps?<br/>
</p>
<p>I appreciate you,<br/>
rabbit</p>
<p><img src="cid:part1.eLPsDRXO.PhCyQCyk@callistohouse.org" alt="" style="width:1180px;max-width:100%" class=""/></p>
<p><br/>
</p>
<div>On 6/22/23 16:21, rabbit via Cuis-dev wrote:<br/>
</div>
<blockquote type="cite">
<p>Hey! I got inspired by your proposal, Luciano,
and here's my solution in eventual promises. Code
can be loaded as:</p>
<blockquote>
<p>Installer ss project: 'Cryptography'; install:
'ProCrypto.release.3'.<br/>
</p>
</blockquote>
<p>I added a test method <br/>
</p>
<blockquote>
<p>RefsTest>>#testMultiReturns<br/>
<br/>
| selectCount unionFlag pair |<br/>
unionFlag := false.<br/>
selectCount := 0.<br/>
((pair := self promiseResolverPair) key
xgcd: 9) <br/>
<<* [:each | selectCount :=
selectCount + 1. Transcript cr; show: 'each = ',
each];<br/>
<<* [:g :s :t | unionFlag := true.
Transcript cr; show: 'g = ', g, '; s = ', s, ';
t = ', t. g + s + t].<br/>
pair value resolve: 21.<br/>
(Delay forMilliseconds: 333) wait.<br/>
self assert: (selectCount == 3).<br/>
self assert: (unionFlag).</p>
</blockquote>
<p>This calls new multireturn #xgcd: method</p>
<blockquote>
<p>xgcd: anInteger<br/>
" 21 xgcd: 9"<br/>
| g s t |<br/>
g := self gcd: anInteger.<br/>
s := self / g.<br/>
t := anInteger / g.<br/>
^ { g. s. t}<br/>
</p>
</blockquote>
<p>And in the test method there are eventual sends
(#<<*) to the promise of the #xgcd: send
once the reciever promise is resolved to 21. This
implementation detects cardinality of the
continuation block and sends #whenResolved:
appropriately, for future evaluation.</p>
<blockquote>
<p>Object>>#<<* continuation<br/>
<br/>
(continuation numArgs == 1)<br/>
ifTrue: [^ self whenResolved: [:result |
result do: [:each | continuation value: each]]].<br/>
^ self whenResolved: [:result | continuation
valueWithArguments: result].</p>
</blockquote>
<p>One can see a 1 cardinality schedules the
continuation to evaluate with each result, while a
continuation with cardinality 2 or more will be
scheduled to receive all results.
#valueWithArguments:</p>
<p>Here are 2 return handlers, <br/>
</p>
<blockquote>
<p>promise := ((pair := self promiseResolverPair)
key xgcd: 9).</p>
</blockquote>
<p>the first for each argument <br/>
</p>
<blockquote>
<p>promise <<* [:each | selectCount :=
selectCount + 1. Transcript cr; show: 'each = ',
each];</p>
</blockquote>
<p>and the second for all three arguments.</p>
<blockquote>
<p>promise <<* [:g :s :t | unionFlag :=
true. Transcript cr; show: 'g = ', g, '; s = ',
s, '; t = ', t. g + s + t].</p>
</blockquote>
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<div>On 6/21/23 09:44, Luciano Notarfrancesco via
Cuis-dev wrote:<br/>
</div>
<blockquote type="cite">
<div dir="auto">Interesting, thanks for sharing!</div>
<div dir="auto">Actually I think it’s the same
thing I did, my implementation calls
BlockClosure>>#valueWithPossibleArgs: and
takes only as many arguments as needed by the
block but the array can be bigger than that (it
should be named #valueWithPossibleArguments:
tho, abbreviations are ugly).</div>
<div dir="auto"><br/>
</div>
<div><br/>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, 21
Jun 2023 at 15:37 Christian Haider via
Cuis-dev <<a href="mailto:cuis-dev@lists.cuis.st" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">cuis-dev@lists.cuis.st</a>>
wrote:<br/>
</div>
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0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div lang="DE">
<div>
<p class="MsoNormal"><span lang="EN-CA">I
added something similar to my Values
package (VW and ports).</span></p>
<p class="MsoNormal"><span lang="EN-CA">The
source is</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA">SequenceableCollection>>asArgumentsIn:
aBlock</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA">
"Evaluate aBlock with the receiver's
elements as parameters.</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> aBlock
takes its arguments from the
receiver.</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> 'ok'</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> #(1 2
3) asArgumentsIn: [:a :b :c | a + b
+ c]</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> #(1 2
3) asArgumentsIn: [:a :b | a + b]</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> #(1 2
3) asArgumentsIn: [:a | a]</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> #(1 2
3) asArgumentsIn: [42]</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> 'not
ok'</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> #(1 2
3) asArgumentsIn: [:a :b :c :d | a +
b + c + d]</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> "</span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> </span></p>
<p class="MsoNormal" style="margin-left:35.4pt"><span style="font-family:"Courier
New"" lang="EN-CA"> ^aBlock
cullWithArguments: self asArray</span><span lang="EN-CA"></span></p>
<p class="MsoNormal"><span lang="EN-CA"> </span></p>
<p class="MsoNormal"><span lang="EN-CA">The
difference is that it takes a list
of any size and picks out the first
items and binds them to the
variables.</span></p>
<p class="MsoNormal"><span lang="EN-CA">I
use it often for CSV processing like</span></p>
<p class="MsoNormal"><span lang="EN-CA">
</span><span lang="EN-CA">(line
tokensBasedOn: $;) asArgumentsIn:
[:first :second :y | … ].</span></p>
<p class="MsoNormal"><span lang="EN-CA"> </span></p>
<p class="MsoNormal"><span lang="EN-CA">I
am just a bit unhappy with the name
– it is too long. It reads ok
though.</span></p>
<p class="MsoNormal"><span lang="EN-CA">The
pipe character is an interesting
idea. I have to think about it.</span></p>
<p class="MsoNormal"><span lang="EN-CA"> </span></p>
<p class="MsoNormal"><span lang="EN-CA">I
am use it for a while now and I am
very happy with it.</span></p>
<p class="MsoNormal"><span lang="EN-CA"> </span></p>
<p class="MsoNormal"><span lang="EN-CA">Happy
hacking,</span></p>
<p class="MsoNormal"><span>Christian</span></p>
</div>
</div>
<div lang="DE">
<div>
<p class="MsoNormal"><span> </span></p>
<p class="MsoNormal"><span> </span></p>
<div style="border-width:1pt medium
medium;border-style:solid none
none;padding:3pt 0cm
0cm;border-color:rgb(225,225,225)
currentcolor currentcolor">
<p class="MsoNormal"><b>Von:</b>
Cuis-dev <<a href="mailto:cuis-dev-bounces@lists.cuis.st" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">cuis-dev-bounces@lists.cuis.st</a>>
<b>Im Auftrag von </b>Luciano
Notarfrancesco via Cuis-dev<br/>
<b>Gesendet:</b> Mittwoch, 21. Juni
2023 15:13<br/>
<b>An:</b> Discussion of Cuis
Smalltalk <<a href="mailto:cuis-dev@lists.cuis.st" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">cuis-dev@lists.cuis.st</a>><br/>
<b>Cc:</b> Luciano Notarfrancesco
<<a href="mailto:luchiano@gmail.com" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">luchiano@gmail.com</a>><br/>
<b>Betreff:</b> [Cuis-dev] Methods
that return multiple values</p>
</div>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Smalltalk doesn’t
have a convention for methods
returning multiple values, and I’m not
aware of any implementation.</p>
<div>
<p class="MsoNormal">An example of
such thing is the extended gcd: ‘a
xgcd: b’ returns g, s, t where g is
the gcd, and as + bt = g. Writing
methods that return multiple values
is easy with the curly brackets
syntax, Integer>>#xgcd: ends
with something like</p>
</div>
<div>
<p class="MsoNormal"> ^ {g. s. t}</p>
</div>
<div>
<p class="MsoNormal">But using sending
messages that return multiple values
is kind of annoying, I end up doing
something like:</p>
</div>
<div>
<p class="MsoNormal"> xgcd := a
xgcd: b.</p>
</div>
<div>
<p class="MsoNormal"> g := xgcd at:
1.</p>
</div>
<div>
<p class="MsoNormal"> s := xgcd at:
2.</p>
</div>
<div>
<p class="MsoNormal"> t := xgcd at:
3</p>
</div>
<div>
<p class="MsoNormal">Some years ago I
thought about using blocks for this,
but I never tried it. Today I just
did a little experiment implementing
anArray | aBlock as ‘^ aBlock
valueWithPossibleArgs: self’ and I
can do:</p>
</div>
<div>
<p class="MsoNormal"> (a xgcd: b) |
[:g :s :t| … ]</p>
</div>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal">This is seems
quite nice already, I guess I’ll
start using it and see how it feels.
But the point of this mail is not to
show a solution, but to ask if
anyone have thought about this or if
they know any nicer solutions. Any
ideas?</p>
</div>
</div>
</div>
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