Re: [Boost-users] [Optional] Lazy initialized optional

Subject: Re: [Boost-users] [Optional] Lazy initialized optional
From: Martijn Otto (boost_at_[hidden])
Date: 2018-11-14 10:03:43

I think using an optional for this is not the right way. Optional has a
storage overhead, because it needs to store whether or not the optional
has a value.

If you derive this class you are going to have this overhead, plus of
course the storage for your callback.

If you do it in a separate class instead, you can clear the callback
after invoking it. Then checking whether a callback exists will tell
you whether the object was initialized.

On Tue, 2018-11-13 at 12:14 -0500, Michael Powell via Boost-users
wrote:
> Hello,
> 
> I am looking into deriving from boost::optional and adding lazy
> initialization capability.
> 
> I can arrange a constructor, or whatever, to inject an appropriate
> factory method, functional callback, etc, that's no problem.
> 
> From the boost::optional perspective, I'd like to override a key
> method (or methods, hopefully not too many) in order to inject that
> factory provided value. I'm thinking optional::get?
> 
> Unless there's a better override for that?
> 
> Cheers,
> 
> Michael Powell
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