[boost] Suggestion for Boost.Function

From: Daryle Walker (dwalker07_at_[hidden])
Date: 2002-11-17 11:45:11

I don't know anything about Boost.Function except what I've seen 
checking out the sample documentations.  I have some thoughts on the == 
and != operators.

You have poisoned (in)equality operators, because of your safe_bool 
type.  Are you using a data pointer type, like "void *" that the 
IOStreams use for their safe-Boolean type?  If so, you should switch to 
an even more useless type.  I used member-pointers for my modulo class 
template (in the Sandbox).

template < int N >
class modulo
{
     typename modulo  self_type;

     int  r_;

public:
     typename int self_type::*  safe_bool;

     operator safe_bool() const;
     //...
};

Here, I used a safe_bool type that was based on the particular version 
of the class template, preventing cross-version comparisons.  I have a 
valid (in)equality operators; if you don't want that either, then 
provide declarations for those operators as member functions, but make 
them private.

Daryle