Re: Abstract Operations On A Tagged Record

[Marin David Condic <nobody@noplace.com>]

BTW: I've been mucking around with this for the last few days and, after 
much struggling, have concluded that attempting to do this (while it may 
indeed work) started becoming entirely too unwieldy. Trying to keep 
stalling off the problems with more and more layers of indirection 
started becoming painful.

What I'm doing is basically leaving those operations out of the base 
class and (where it makes sense) I'm creating layer(s) of intermediate 
classes that get more and more specific about what the required 
parameter types are. Its still rather "heavy" (you have to keep 
isolating things in more packages and creating more branches in the 
class tree) but it seemed less painful than trying to find all the 
necessary abstractions & provide all the needed operations on the 
parameter class.

Sometimes you just have to bite the bullet and say "here's a version 
that deals with a float and here's a version that deals with a boolean 
and its just not worth the pain of trying to make them both be the same 
thing..." But at least I got a better understanding of what I'm dealing 
with, eh?

MDC



Nick Roberts wrote:
> 
> I'm fairly certain that you require something like:
> 
>   procedure Some_Op (The_Thing : in out Some_Tagged_Type;
>                      The_Params: in     Some_Parameter_Type'Class)
>                                                          is abstract ;
> 


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Marin David Condic
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