[rules-dev] Drools syntax diagrams - redrawn

[Michael Neale]

The $name: Pattern thing I am convinced is to do with Mark's prior history
of being abused by perl ;)

But the real reason is we wanted to use ?name: Pattern() - using "?" like
the clips lineage of languages - but IIRC even ilog allows that. We wanted
our labels to be compatible with java source code - where $variable is a
valid name (although no one actually uses it) and ?name is not.

So here we are ;)


On Fri, Sep 24, 2010 at 12:29 AM, Greg Barton <greg_barton at yahoo.com> wrote:

> Yes, and I don't think we want to take readability cues from Perl. :)
>
> GreG
>
> On Sep 23, 2010, at 3:03, Wolfgang Laun <wolfgang.laun at gmail.com> wrote:
>
> On 23 September 2010 09:31, Bruno Unna < <bruno.unna at gmail.com>
> bruno.unna at gmail.com> wrote:
>
>> FWIW: in Perl, there are both operators as well (|| and 'or'). However,
>> they are *not* exactly the same. Although they can be used in any context to
>> render a boolean expression, their priority makes the difference. Taken from
>> official documentation ( <http://bit.ly/dgw4GT>http://bit.ly/dgw4GT):
>>
>>
> Low precedence "and", "or", "xor" were introduced to permit "Perl poetry",
> or, more seriously, to
> permit control flow using a logical expression, especially after function
> calls without parentheses.
>    see Naples or die;  # same as: see(Napes) || die(); but not: see(Naples
> || die() );
>
> No way this makes any sense in Drools.
>
> -W
>
> Binary "or" returns the logical disjunction of the two surrounding
>> expressions. It's equivalent to || except for the very low precedence. This
>> makes it useful for control flow.
>>
>>
>> Nonetheless, it must be taken into account that the distinction makes
>> sense for a Perl programmer. For a rules-writing guy (or girl) perhaps the
>> distinction is extremely obscure.
>>
>> Regards.
>>
>>
>>
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-- 
Michael D Neale
home: www.michaelneale.net
blog: michaelneale.blogspot.com
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