[rules-dev] @metadata: status; compatibility issues

[Wolfgang Laun]

On 29 April 2011 19:18, Edson Tirelli <ed.tirelli at gmail.com> wrote:

>
>    Wolfgang,
>
>    It seems to me that what we need to to improve the solution to address
> the problems you listed, but we are better now then we were before, as we
> support everything that was supported in 5.1 + the new use cases.
>

Correct!



>
>    Did I miss something?
>
> Only if you intend to do, in a later release, s.th. with those
expressions, such as evaluate them if they are all literal, or maybe with
imported variables, if that can be done at all. If yes, the thing I'd
propose is to either announce (clearly!) the future change ("expressions
will not remain expressions returned as Strings") OR reduce the accepted
expressions to single literals of the basic types, which could be converted
to Integer/String/Boolean objects according to their natural syntax.

Perhaps the concatenation of duplicated inner Map values should be removed -
I'm afraid I did that, in an effort to avoid silent overwriting, which
definitely isn't better; both is bad.

Wolfgang


>    Edson
>
> 2011/4/29 Wolfgang Laun <wolfgang.laun at gmail.com>
>
>> The current parser handles metadata annotations
>>
>>   '@' *Identifier* '(' *Text* ')'
>>
>> so that the annotations for one entity (e.g., a rule) are available as a
>> Map<String,Object>, where the key is given by the *Identifier *and the
>> value of the entry is available according to
>>
>> *if*  *Text* can be *completely* parsed as   *Identifier* '=' *Expression
>> * (where  *Expression*  is whatever the DRL parser accepts as an
>> expression, i.e., an extended subset of Java expressions)
>>    *then*
>>       the value is a Map<String,String>
>>    *else
>>      the *value is a String, with trimmed leading and trailing white
>> space, but preserving all embedded white space
>>
>> Changes compared to 5.1.1:
>>    - no Map was ever returned in 5.1.1,
>>    - @m( "foo" ) in 5.1.1. returned "foo", but 5.2.0 returns "\"foo\"".
>>    - @m( "foo", "bar" ) in 5.1.1. returned "foo\", \"bar", but 5.2.0
>> returns "\"foo\", \"bar\""
>>    - comments between "@...(" and ")" are now handled consistently but
>> were not in 5.1.1
>>
>> Possibly considered a problem for 5.2.0 or later:
>> - No check is made for duplicate "outer" map keys; entries are
>> overwritten.
>> - Repeated "inner" map keys produce concatenated entries, e.g. @m( k = 1,
>> k = "a" ) returns "1a" as the value for key "k".
>> - Returning (arbitrary) expressions, unchanged, as String now may cause
>> incompatibilitie with more sophisticated processing (if this ever should be
>> considered).
>>
>> -W
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>>
>>
>
>
> --
>   Edson Tirelli
>   JBoss Drools Core Development
>   JBoss by Red Hat @ www.jboss.com
>
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