Re: [boost] Interest in dimension/unit-checking library?

From: Matt Calabrese (rivorus_at_[hidden])
Date: 2005-10-20 15:26:36

On 10/20/05, Matt Calabrese <rivorus_at_[hidden]> wrote:

> I'd say it's much more analogous to conversions in C++ from a short
> unsigned int to an unsigned int being implicit. You don't lose any
> information in the conversion and the conversion makes perfectly logical
> sense. Forcing users to always be explicit is just making them write more
> unecessary code.
>

Also, expanding on this analogy since I don't think you are understanding
the point I'm trying to make -- one might have code which uses shorts and
ints to represt two different high-level concepts in code. In that
particular project, under your logic, you wouldn't want implicit conversion
from short to int. This is literally exactly the same situation with units.
The "problem" isn't because short to int conversions should be explicit,
it's because you aren't representing the high-level concepts which actually
use those types as implementation details in your code. You really should be
encapsulating those values in two different types if that is the
functionality you want.

The same situation can occur if both values were represented with ints. The
operation between the two ints still wouldn't make sense -- the problem is
that you aren't representing the fact that they implementation details of
higher level concepts in your code. Encapsulation is what you really want.
Always making short int to int conversions be explicit is missing the point
that the datatype isn't the reason why the two objects aren't addable. The
reason is because there is a higher level of abstraction which you didn not
represent.

--
-Matt Calabrese