[Pharo-project] About changes and so on: Authorize - at any position in binary selectors (like VW 7.7)

Igor Stasenko siguctua at gmail.com
Wed Feb 24 03:28:58 EST 2010


On 24 February 2010 10:15, Nicolas Cellier
<nicolas.cellier.aka.nice at gmail.com> wrote:
> 2010/2/24 Lukas Renggli <renggli at gmail.com>:
>>> Huh? I am always assumed that binary selectors parsed in greedy
>>> manner, which means that if parser found the start of
>>> binary selector, it scans forward for following characters which can
>>> be part of selector, without exceptions, like '-' char..
>>
>> I checked in the ANSI standard. Igor is right:
>>
>> == ANSI: 3.5.6 Numbers ======
>>
>>  binaryCharacter ::= '!' | '%' | '&'' | '*' | '+' | ','' | '/' | '<'
>> | '=' | '>' | '?' | '@' | '\' | '~' | '|' | '-'
>>  binarySelector ::= binaryCharacter+
>>
>> Binary selectors are method selectors that appear similar to
>> mathematical operators. A binary selector may be any length greater
>> than or equal to one. If a negative <number literal> follows a binary
>> selector there must intervening white space."
>>
>> =========================
>>
>> I somehow remembered the grammar differently and that the $- was only
>> allowed in the first position. This doesn't seem to be the case though
>> (any longer) :-/
>>
>> I am not against changing the grammar to conform to ANSI and VW. I
>> think that would actually be a good move, even if it is probably not
>> really relevant in practice. I am however strongly against asking the
>> user to disambiguate an expression. The compiler should compile what
>> the user types, not guess what else he could have ment to say.
>>
>> Lukas
>>
>
> Then the question is how you compile 1 at -2 and how you provide backward
> compatibility.
>

As i said, i was always assumed that our parser works as ANSI says..
So, personally, i don't care about those who not followed it :)
But yes, compatibility is now an issue :(

Darn, why introducing a non-uniformity in syntax in a such way?
When i hearing "hey, smalltalk expressions don't follow the 'usual'
operators order of priority", i was always said - we don't need a
non-uniform rules which complicating the syntax! But now , what a
shame.. we actually having those! :)

> Nicolas
>
>> --
>> Lukas Renggli
>> http://www.lukas-renggli.ch
>>
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>
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-- 
Best regards,
Igor Stasenko AKA sig.




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