Subject: [Boost-bugs] [Boost C++ Libraries] #4582: fold() doesn't work with function objects that don't support perfect forwarding
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-08-21 18:52:29
#4582: fold() doesn't work with function objects that don't support perfect
forwarding
-------------------------------------+--------------------------------------
Reporter: anonymous | Owner: djowel
Type: Bugs | Status: new
Milestone: To Be Determined | Component: fusion
Version: Boost Development Trunk | Severity: Problem
Keywords: |
-------------------------------------+--------------------------------------
the unrolled specializations of fold() are implemented as
{{{
f(f(f(state,a),b),c)
}}}
if f is a function object that doesn't support perfect forwarding, but
only accepts "T &" arguments, this doesn't work.
this is e.g. the case for all phoenix::bind() results:
{{{
int f(int,int,int){ return 0; }
int main(){
fusion::vector<int,int> vec;
fusion::fold(vec,0,phoenix::bind(&f,_1,_2,3)); //error
}
}}}
AFAIK a bind() cannot support perfect forwarding and at the same time
support the result_of protocol, not even for up to 2 arguments as
Boost.Bind does.
attached is a patch that changes that.
-- Ticket URL: <https://svn.boost.org/trac/boost/ticket/4582> Boost C++ Libraries <http://www.boost.org/> Boost provides free peer-reviewed portable C++ source libraries.
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