Re: OO in Ada

[Jim Rogers <jimmaureenrogers@worldnet.att.net>]

Dmitry A.Kazakov wrote:

> Jim Rogers wrote:
> 
> 
>>I disagree here. Ada does not give the illusion of multiple dispatch.
>>
> 
> Would "limited multiple dispatch" sound better?
> 
> 
>>An Ada subprogram can only be primitive to one type. That characteristic
>>is determined by the place in the source code where the subprogram
>>interface is defined.
>>
> 
> This is wrong. Technically you could do it, because type declaration areas 
> [before freezing point] may overlap:


I must again diagree. You are wrong. Section 3.9 paragraph 12 of the Ada
Reference Manual states:

"A given subprogram shall not be a dispatching operation of two or more distinct 
tagged types."



> 
> type A is tagged ...
> type B is tagged ...
> procedure Multiple_Dispatch (X : A; Y : B); -- Alas, compilation error


There is a compilation error. Look at what it says. Gnat 3.14p states
"operation can be dispatching in only one type."

This does not provide any for of multiple dispatch, limited or otherwise.