Re: [Boost-users] [serialization] compile-time detection of whether serialization is implemented for a class

Subject: Re: [Boost-users] [serialization] compile-time detection of whether serialization is implemented for a class
From: Nelson, Erik - 2 (erik.l.nelson_at_[hidden])
Date: 2012-02-16 15:41:35

Ioannis Papadopoulos wrote
> On 02/16/2012 08:45 AM, Nelson, Erik - 2 wrote:
> >
> > What I'd like is a compile-time way of detecting that 'A' is not
> > serializable, maybe Boost Type Traits-style, something like
> >
> > is_serializable<A>::value or is_serializable<binary_oarchive,
> A>::value that can detect whether or not the object has serialization
> available.
> >
> > If it could work for testing pointer serialization as well
> (is_serializable<A*>::value or is_ptr_serializable<A>::value) that
> would be doubly super.
> >
> 
> I was trying to do something like that before. The problem is that
> 1) serialize() might be private so any metaprogramming trick you are
> going to try will be met with a compiler error
> 2) how do you detect if serialization is supported using a non-
> intrusive way? I made a relevant question some time ago and requires
> decltype :(
> 
> Some additional discussion:
> http://lists.boost.org/Archives/boost/2010/10/172236.php
> 
> Bottom line, I don't think it can happen without assistance from
> Boost.Serialization
> 
Thanks for the link- that looks pretty close to what I'm trying to do.  It seems to me it should be possible... after all, the compiler knows if the serialization is available.  If you write

ar << my_type;

and my_type is not serializable (either intrusively or not) the compile will fail.  And if I do something like

typedef boost::archive::binary_oarchive Archive;
typedef boost::archive::detail::interface_oarchive<boost::archive::binary_oarchive> interface_t;
typedef Archive& (interface_t::*functype)(A &);
Archive& (interface_t::*ptr1)(A &) = &interface_t::operator<<;

Taking the address of operator<< will fail if serialization is not somehow available.  It seems like turning that compile-time error into a compile-time trait might be possible, but I don't know exactly how.

Erik

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