Re: [Boost-users] boost bind, issue moving from 1.57 to 1.60

Subject: Re: [Boost-users] boost bind, issue moving from 1.57 to 1.60
From: Piotr Kowalski (koval.gnu_at_[hidden])
Date: 2016-06-16 20:27:04

Under Visual Studio C++ 2013 the example works fine after adding a
reference in function signature:
boost::function<bool(boost::shared_ptr<const Boom>&)>

This somehow prevents too much forwarding and losing the original value

2016-06-17 1:29 GMT+02:00 Gavin Lambert <gavinl_at_[hidden]>:

> On 17/06/2016 09:39, Jason Mancini wrote:
>
>> So this snippet comes from a sizable code base.  Took a long time to
>> pinpoint then distill the issue down to the 6-line example!  Pretty sure
>> that std::bind / std::function don't support this usage, or at least it
>> didn't work when I tried for a few minutes.  Boost flavor seems a bit
>> more featured.
>>
>
> Yeah, boost::bind supports quite a few late-binding operators, which are
> handy to improve code brevity but can be a bit confusing to read.  If
> you're using a C++11 compiler then it's probably better to use lambdas for
> these cases now.
>
> The actual offender is the bigger change in bind/bind.hpp from 1.59 to
>> 1.60 (not the trivial changes in args or placeholder).  I can see they
>> added significant std::forward / rvalue support.  If I set
>> BOOST_NO_CXX11_RVALUE_REFERENCES then also it continues to work.  I
>> suspect we've hit a corner case issue with forward / rvalue and
>> boost::function / boost::shared_ptr.
>>
>
> Most likely, somewhere along the way it's moving the pointer and then
> returning the original instead of the new one.
>
>
>
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