[boost] Re: 3-state boolean type

From: Nicola Musatti (Nicola.Musatti_at_[hidden])
Date: 2002-08-02 10:49:05

Peter Simons wrote:
> 
> Just curious: Shouldn't the property of a variable being unset or being
> set (and having a value in the latter case) be usable more generally?

I was about to express a similar point of view. In my case I have to
represent values read in from a database where fields could be null. I
need an explicit representation because I'm working on an intermediate
layer and the decision on how to represent these (missing) values
belongs in the presentation one.

I'm currently tackling this problem by providing a template wrapper that
lets you specify a conventional value to represent nulls or adds a
boolean field if a suitable value is not available in the base type.

Cheers,
Nicola Musatti