[squeak-dev] The Inbox: ShoutCore-ct.69.mcz

John Pfersich smalltalker2 at mac.com
Mon Aug 19 01:37:21 UTC 2019


The full definition from the draft standards (don’t have the standard handy) is:

<block constructor> ::= '[' <block body> ']'
<block body> ::= [<block argument>* '|'] [<temporaries>] [<statements>]
<block argument> ::= ':' identifier

The last line is on the next page of the draft.

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> On Aug 18, 2019, at 12:09, JOHN SARKELA via Squeak-dev <squeak-dev at lists.squeakfoundation.org> wrote:
> 
> The ANSI standard has the following rules for blocks:
> <block constructor> ::= '[' <block body> ']'
> <block body> ::= [<block argument>* '|'] [<temporaries>] [<statements>]
> 
> The standard does not recognize [:x] as legal syntax for a block.<page21image64736448.png> <page21image37471328.png> <page21image64735680.png> <page21image64733952.png> <page21image64746816.png>
> 
>> On Aug 18, 2019, at 3:03 PM, Levente Uzonyi <leves at caesar.elte.hu> wrote:
>> 
>> Hi Nicolas,
>> 
>> Thanks for investigating this.
>> I still think that it's just a parser bug, which is accidentally "used" sometimes, especially because it only works when the block is empty.
>> Or does it work in other dialects with non-empty blocks?
>> Is it used in other dialects?
>> 
>> Levente
>> 
>>> On Sun, 18 Aug 2019, Nicolas Cellier wrote:
>>> 
>>> Le jeu. 15 août 2019 à 12:21, Levente Uzonyi <leves at caesar.elte.hu> a écrit :
>>>      On Thu, 15 Aug 2019, Tobias Pape wrote:
>>> 
>>>      >
>>>      >> On 15.08.2019, at 03:29, Levente Uzonyi <leves at caesar.elte.hu> wrote:
>>>      >>
>>>      >> On Wed, 14 Aug 2019, commits at source.squeak.org wrote:
>>>      >>
>>>      >>> A new version of ShoutCore was added to project The Inbox:
>>>      >>> http://source.squeak.org/inbox/ShoutCore-ct.69.mcz
>>>      >>>
>>>      >>> ==================== Summary ====================
>>>      >>>
>>>      >>> Name: ShoutCore-ct.69
>>>      >>> Author: ct
>>>      >>> Time: 14 August 2019, 10:43:04.7164 pm
>>>      >>> UUID: 7d165f4e-09bf-a445-a664-5e8edb9867b8
>>>      >>> Ancestors: ShoutCore-ul.68
>>>      >>>
>>>      >>> Fix bug in SHParserST80: Wrong styling after blocks with arguments without statements
>>>      >>
>>>      >> If you mean that Shout should accept [ :x ], then no, I'm pretty sure that's not valid smalltalk syntax, even if Parser accepts it.
>>>      >> The vertical bar, even though I consider it unnecessary in all cases, is mandatory when there are arguments.
>>>      >
>>>      > I only got to know this "shortcut syntax" because eliot used it either Cog or somewhere in trunk when preparing something (Spur? full block closures? I forgot). So this is a syntax idiosyncrasy that is in active use, not only "old code".
>>>      >
>>>      > Either we forbid it in the parser and change all of the image or allow it in Shout.
>>> 
>>>      Can you give me examples?
>>>      I suspect those are just typos, which the parser accidentally accepted
>>>      (and Shout as well before my fixes).
>>> 
>>>      Levente
>>> I don't remember seeing this syntax before and found it a bit surprising.
>>> So, for the sake of curiosity, I tried in some other dialects.
>>> [:x ] is accepted syntax in
>>> - Visualworks (8.3),
>>> - Pharo (v7 with OpalCompiler)
>>> - Smalltalk-80 (apple v0.?)
>>> [:x ] is invalid in
>>> - Dolphin
>>> - Smalltalk/X (jv branch)
>>> So it seems that it's something originating from original Smalltalk-80, but not reproducted in non derivated dialects...
>>> The bar is mandatory in blue book specification (see the last pages)
>>> Capture d’écran 2019-08-18 à 17.11.53.png
>>> So it seems that implementation did not agree with specifications for ages...
>>> Capture d’écran 2019-08-18 à 18.56.05.png
>>> 
>>>      >
>>>      > Best regards
>>>      >       -Tobias
>>>      >
>>>      >>
>>>      >> Levente
>>>      >>
>>>      >>>
>>>      >>> Thanks Jakob for the report!
>>>      >>>
>>>      >>> =============== Diff against ShoutCore-ul.68 ===============
>>>      >>>
>>>      >>> Item was changed:
>>>      >>> ----- Method: SHParserST80>>parseBlockArguments (in category 'parse') -----
>>>      >>> parseBlockArguments
>>>      >>>
>>>      >>>     currentTokenFirst == $: ifFalse: [ ^self ].
>>>      >>>     [ currentTokenFirst == $: ] whileTrue: [
>>>      >>>             self
>>>      >>>                     scanPast: #blockArgColon;
>>>      >>>                     parseArgument: #blockPatternArg ].
>>>      >>> +   ((self parseVerticalBarForTemporaries: #blockArgsBar) and: [
>>>      >>> +           currentTokenFirst ~= $] ])
>>>      >>> +                   ifFalse: [
>>>      >>> +                           self fail ": Missing block args bar" ]!
>>>      >>> -   (self parseVerticalBarForTemporaries: #blockArgsBar) ifFalse: [
>>>      >>> -           self fail ": Missing block args bar" ]!
>>>      >>
> 
> 
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