Re: Booch: iterator invalidation

[porton@ex-code.com (Victor Porton)]

In article <uel9p8qms.fsf@gsfc.nasa.gov>,
	Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov> writes:
> porton@ex-code.com (Victor Porton) writes:
> 
>> >> type T is T_Internal(Use_Debug); -- Use_Debug is a Boolean _constant_
>> >> 
>> >> Will this not bring "additional debugging stuff" in the release
>> >> version (when Use_Debug=False)?
>> > 
>> > Now everything that uses T_Internal has to specify a Debug
>> > discriminant. To intrusive for my taste.
>> 
>> It is meant for user code to use _only_ T, not T_Internal.
>> (In OO style T_Internal should be in private section.)
> 
>> All compiler implementors should consider this to ensure that
>> they have zero space-efficiency.
> 
> I'm not clear what you mean here. I suppose if the compiler could
> prove that _every_ instance of T_Internal had the same value for
> Use_Debug, it could optimize stuff. But that seems like a lot of work.
> Any time T_Internal is passed as a subprogram parameter, you'd either
> have to inline the subprogram or do full data-flow analysis.

I meant the case when _all_ except of debug (like Dump, Check, 
Throw_If_Invalid) rountines use only T, not T_Internal.