RE: [boost] boost::lambda::operator* and smart pointers

From: Eyal Farago (eyal.farago_at_[hidden])
Date: 2004-03-21 04:06:30

I think this level of indirection is already encapsulated in boost::pointee.

eyal.

-----Original Message-----
From: Maxim Yegorushkin [mailto:e-maxim_at_[hidden]]
Sent: Saturday, March 20, 2004 4:50 AM
To: boost_at_[hidden]
Subject: [boost] boost::lambda::operator* and smart pointers

Hi guys.

I encountered a pitfall when trying to use boost::lambda for dereferencing a smart pointer. Current lambda implementation assumes that operator*() can be applied to either a plain pointer or an iterator. That leads to an error message when applying the operator to a smart pointer complaining about std::iterator_traits<> not being specialized for the smart pointer.

Consider the code:

struct some
{
     void foo(int);
};

boost::shared_ptr<some> ptr(new some);

(
lm::bind(
       &some::foo
     , *lm::_1
     , 0
     )
)
(ptr);

the bind expression won’t compile until we hack std::iterator_traits<boost::shared_ptr<> >:

template<class T>
struct std::iterator_traits<boost::shared_ptr<T> > : std::iterator<void, T>
{
};

My point is: why don’t add an additional level of indirection for boost::lambda::detail::contentsof_type<> so that the indirection will allow the user to specialize it for smart pointers?

-- 
Maxim Yegorushkin
MetaCommunications Engineering
http://www.meta-comm.com/engineering/
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