Re: package Ada.Tags

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Thu, 07 Jun 2012 23:35:11 +0200, Simon Wright <simon@pushface.org> a  
écrit:

> "RasikaSrinivasan@gmail.com" <RasikaSrinivasan@gmail.com> writes:
>
>>    procedure show (event : events_record_type) is
>>       use GNAT.Calendar.Time_IO;
>>    begin
>>       put( ada.Tags.Expanded_Name( event'tag ) );
>>       put( gnat.Calendar.time_io.Image( event.time ,  
>> gnat.Calendar.Time_IO.ISO_Date & " %T")) ;
>>    end show;
>>
>> gives me a compilation error:
>>
>> "tag" attribute can only be applied to objects of class - wide type.
>>
>> In the above, isnt event an object meeting this criterion?
>>
>> clearly i am missing something. The question is I want to find out the
>> equivalent of RTTI from C++. ie Which one if the derived types is it.
>
> You can get it to compile by converting the object 'event' of a specific
> type to the class-wide type:
>
>   Events_Record_Type'Class (Event)'Tag

Forgive me for being pedantic, but it's important to note this is not a  
type conversion, that's a *view conversion*.

-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University