Re: [boost] Re: [Boost-announce] Formal Review Tribool

From: Doug Gregor (gregod_at_[hidden])
Date: 2004-06-05 10:09:14

----- Original Message ----- 
From: "Haim Cohen" <haim.cohen_at_[hidden]>
> First of all, my first comment is about the library's name, as well as the
class name.
> In logic circuit simulation, there are 4 values : 0, 1, x ( which is
tribool referred to as undetermine ), and z ( represents high impedance - or
> disconnection, and sometime referred to as "tri state" ).
> So, I think users will find it quite confusing when they see the 'tri' in
the library's name.
> Since the library implements a logic value which has some value that is
unknown, I would suggest 'unknown bool' or 'x bool'.
>
> Now to the interface.
> I think that a macro which enables renaming of the x value should not be
supplied. This will make people's code less standard.

Ironically, it was disagreements over the name of the 3rd state that
resulted in the macro, although I think I agree with you. Users may just
have to deal with our choice of name (for their own good <g>).

> Same as we all know what 'true' and 'false' mean, we should adopt a unique
name for 'unknown yet quite determined logic value'.
> I think the default 'undetermine' name is not a good name.
> My suggestions : logic_x, x_value, x_logic, unknwon_bool .

I agree with Rob Stewart's comments about using "x". As for "unknown", I'm
pretty flexible: tribool originally had "unknown", but I seem to recall that
earlier informal review favored "indeterminate".

>> Some point for thought : Users might want arrays of tribools, with all
the support of bitwise operations.
> Is this should be a part of tribool as well ? I do not know.

I think this would be a useful feature, and I believe Pavel (?) had
mentioned interest in writing something like this. It would probably be
similar to dynamic_bitset.

[snip]
> So, I suggest to change implementation to use class-static fixed array to
perform calculations.

Agreed.

> I hope this review would be found useful.

Absolutely. Thank you.

    Doug