Angus Leeming <[EMAIL PROTECTED]> writes:
| Lars Gullik Bjønnes wrote:
>> I even think boost::optional should be used for the Cached vars
>> type, then you can easily know if the cached var is set or not.
>>
>> template <typename T>
>> class CachedVar {
>> public:
>> CachedVar(CachedVar const &) { var_.reset(); }
>> void operator=(CachedVar const &) { var_.reset(); }
>>
>> CachedVar() {}
>> void operator=(T const & var) { var_.reset(var); }
>> operator T() const { return *var_; }
>> private:
>> boost::optional<T> var_;
>> };
>
| I'm not so sure. Apart from the fact that I don't know what the result
| of '*var_' is when the variable is not set, I think it is always true
| that 'T()' is a perfectly valid result here. See how we use cached
| variables.
CachedVar<int> cache_;
Really non-usable, but has a value that should not be used. Perfect
use of optional. I am very sure.
T() is not a valid result if it was not set by values that should
actually be cached... So it is also a safety measure.
--
Lgb
