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Subject: Re: [boost] safe bool operator
From: Domagoj Saric (dsaritz_at_[hidden])
Date: 2010-03-01 16:47:17

"Peter Dimov" <pdimov_at_[hidden]> wrote in message
news:A062A9144EEA45339956BFD0D4FDC906_at_pdimov2...
> Using a single type allows unrelated classes to compare equal with
> operator==.

Do'h :)

Even if I thought of that I would have thought that the
'only-a-single-conversion-may-take-place' rule would apply...Thanks for the
correction ;)

...but still the proposal can work, only in the usual template-uglified form:

class my_class
{
public:
    bool some_is_valid_function() const;

    operator boost::safe_bool<my_class>::type() const { return
        boost::safe_bool<my_class>::make( some_is_valid_function() ); }

    //or by using a macro
    BOOST_SAFE_BOOL_FROM_FUNCTION( my_class, some_is_valid_function() );

    //or by using a data member
    unsigned int size_;

    operator boost::safe_bool<my_class>::type() const { return
        boost::safe_bool<my_class>::make( size_ ); }
    BOOST_SAFE_BOOL_FROM_DATA( my_class, size_ );
}

...still less hassle than status quo...

...or maybe even more so if we take advantage of the fact that now we can use
the CRTP idiom (or part of it):

class my_class : boost::safe_bool<my_class>
{
public:
    bool some_is_valid_function() const;

    operator unspecified_bool_type() const { return make(
        some_is_valid_function() ); }
} 

--
"What Huxley teaches is that in the age of advanced technology, spiritual
devastation is more likely to come from an enemy with a smiling face than from
one whose countenance exudes suspicion and hate."
Neil Postman 
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`
end
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