Re: [Boost-users] boost::bind and Motif

Subject: Re: [Boost-users] boost::bind and Motif
From: Andrew Holden (aholden_at_[hidden])
Date: 2012-05-04 09:33:44

On Thursday, May 03, 2012 2:42 PM, Richard wrote:
> boost-users_at_[hidden] spake the secret code
<1D97E025367AFB4A8C528590A3715BF442603A_at_archerysummit2.willamette.charte
roaksystems.com> thusly:
>
>>	static void Internal_callback (XtPointer self, XtIntervalId*)
>>	{
>>		reinterpret_cast <AppTimeout*> (self)->callback();
>
> I don't know why people always leap to reinterpret_cast<> as their
> first choice; it's the most dangerous.  I'd prefer static_cast<> here.

In this case, the reinterpret_cast is needed because X11 specified that
your callback *must* take a void pointer.  Reinterpret_cast and the old
c-style cast (which would act as a reinterpret_cast in this case) are
the only ways I know to convert a void pointer to the correct type.  In
this case, I mitigated the danger by making Internal_callback private
and ensuring the only place where it is used--the public Schedule
function--provides a pointer of the correct type.