Boost Users :
Subject: [Boost-users] Delegating to boost::function with arbitrary signature
From: Alexander Lamaison (awl03_at_[hidden])
Date: 2013-12-14 09:49:37
I've asked this question on Stack Overflow but not found a solution yet:
Boost.Function/MPL-related so I'll ask here too.
I'm trying to create something like a `boost::function`, but with an
extra 'smart handle' tucked inside, which controls the lifetime of a
resource the functions needs to execute correctly.
If I didn't need the function signature to be completely generic, this
would be easy. I would just create a functor with the correct
signature, and keep a `boost::function` and the handle as members.
However, I do need generic signatures. The code below is as close as
I've got but gets a compile error, presumably, because I'm not able to
unpack a list of arguments like this:
boost::function<result_type(arg1_type, arg2_type)> function)
typename result_type operator()(arg1_type arg1, arg2_type arg2)
return m_function(arg1, arg2);
// I don't think I can declare the 'params' like this ...
typename boost::function_types::result_type<Signature>::type operator()(
return m_function(params); // ... nor unpack them like this
I think `params` is an MPL list, so what I've actually done is declare a
call operator with a single MPL-list parameter. My MPL-foo is not good.
Is there a way to convert the list to a legal definition of multiple
A suggested solution on SO is to use `boost::bind`, but I still don't
see how to bind an arbitrary number of arguments.
All advice greatly appreciated.
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