Re: [boost] [review] Fast track review of Boost.Utility/Singleton - ctor question

From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2008-01-23 06:52:06

Kowalke Oliver (QD IT PA AS) wrote:
> Hi Tobias,
> how does Boost.Utility/Singleton solve the problem if the singleton calss itself needs arguments in its ctor (for instance if I want to use the RAII pattern)?

Not at all, you have to solve it yourself.

So reading from you post you have a class you can't (or don't want to) 
change, that needs arguments in the ctor. You can make a Singleton from 
that class using multiple inheritance.

     class a_singleton : public boost::singleton< a_singleton >,
         public my_class
     {
         a_singleton(boost::restricted) : my_class( /* args go here */ )
         {
         }
     };

Parameterizing the static 'instance' method of a classic Singleton take 
is a bad idea IMO, because it causes redundancy all over the place.

Regards,
Tobias