Re: Overloading attributes

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

Le Sun, 27 Nov 2011 00:24:08 +0100, Shark8 <onewingedshark@gmail.com> a  
écrit:
> You can write an function to replace 'Image, it's a rather a good
> question you bring up because it can also be stated:
> "why are 'Read & 'Write required to have an attribute definition
> clause,
>  but 'Image is not (in fact it is forbidden)?"

Personal opinion: something similar to what I replied to Dmitry some days  
ago, about not blindly applying any schema to anything. A case by case  
investigation shows 'Read and 'Write are useful to persistent storage and  
can be used internally by the Ada runtime or standard library. Image is  
not, and is all in user space only. So there is no formal need to be able  
to say “for X'Image” use, because the runtime, nor the standard library,  
will never use it, and as only the user will access it, the user can as  
much define an “function Image (X : …) return String_Or_Whatever_Type;”.  
Similarly, the runtime will make use of Storage (via “new T”), so the  
’Storage attribute can be redefined by the user.

It's all a matter of “is this just toy or it this formally required ?”. A  
user re-definable Image attribute is not needed for the language, so it's  
up to the user to deal with it at user level.

P.S. I feel the sole use of 'Image I know, is for quick debugging output  
of something. Otherwise, if you need to write a text representation of an  
entity to some file, you should go with a custom procedure or function.

-- 
“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]