Re: [Boost-users] Beginner question: Why boost::signal creates another instance of the slot object ?

Subject: Re: [Boost-users] Beginner question: Why boost::signal creates another instance of the slot object ?
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-08-19 20:29:20

AMDG

Mauricio Gomes wrote:
> Thank you very much Steven, boost::ref worked fine.
>
> Just for my education, what is the rationale behind making a copy of
> the signaled object ?
> It seems odd to me since the object interested in receiving the event
> ends up not receiving it (unless we use boost::ref).
>   

Passing function objects by value is the normal
convention in C++.  There are many cases where
it is the correct behavior.  For example, if you
you connect a function object created by boost::bind
to the signal, the function object is a temporary and
is destroyed immediately.  If it were stored by
reference, the boost::signal would be left with
an invalid reference.  Don't think of the function
object as the object receiving the signal.  The
function object is an action to be performed.

> I am obviously missing something conceptually here. If you or anyone
> could explain it to me I'd really appreciate.
>   

In Christ,
Steven Watanabe