[Boost-users] Re: Re: boost::unary_traits

From: Ian McCulloch (ianmcc_at_[hidden])
Date: 2005-03-07 13:31:49

John Maddock wrote:

>> Anything else coming to your mind what could be bad about this adaptor? I
>> want it to be as robust as possible because I intend to use it a lot.
> 
> You need to add the const declaretor, *after* you remove the reference
> (adding cv-qualifiers to reference types has no effect).
> 

No, that gives a different effect to what I intended.  The task is to take
an argument_type that could be either a value or a reference, and convert
it to a corresponding pointer type.  If the argument_type is a (const or
non-const) reference, then simply removing the reference is what is
required.  Adding const after that would fail for argument_type's that are
non-const references as *ptr would be a reference to a const.

Conversely, if argument_type is not a reference, then the pointer type
should be a pointer to const, because the argument will be copied anyway so
there is no reason to forbid using it with const objects.

Unless I missed something, adding const followed by removing reference
should achieve this.

Cheers,
Ian