Re: Overring function and its returned type

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

Le Fri, 09 Nov 2012 14:11:38 +0100, Dmitry A. Kazakov  
<mailbox@dmitry-kazakov.de> a écrit:
> A more general question is about overriding out-operations to narrower
> subtypes, and/or overriding in-operations to wider subtypes. That could
> work.

Nice to read this. Made me think of it too, with the added rule that `in  
out` would need to be fixed in overriding methods and not change their  
type. However, about `out` mode, that may be more easy with function  
returned object than with object “returned” by an `out` parameter. An  
`out` parameter may not be updated as a whole, which is required for  
example to change the type of a discriminated type with default  
discriminants. The function result case is safer because more predictive.  
Or else, would have to require some `out` parameters to be updated as a  
whole.

-- 
“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