Re: Seeking for papers about tagged types vs access to subprograms

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

Le Fri, 10 May 2013 05:29:53 +0200, Yannick Duchêne (Hibou57)  
<yannick_duchene@yahoo.fr> a écrit:
> […] A simple example, is paired invocation, where whenever a sub‑program  
> is is invoked, sooner or later, another sub‑program must be invoked too  
> on the same argument, ex. like `Open` and later `Close`. This cannot be  
> expressed with types and indeed requires assertions.
>
> But saying “weak” may be erroneously interpreted, and then, the type is  
> still the first place to holds the validity rules. In the example above,  
> the paired invocation requirement, could be expressed in the type owning  
> these two primitives […]

No, what I said on this is wrong, due to lack of precision. This have to  
be an assertion on the outer level, the state of the enclosing scope of  
the operations (an implicit value which cannot be explicitly referred to  
as a whole with Ada).

-- 
“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