Adam Butcher-2 wrote:
On Tue, March 1, 2011 4:38 pm, lcaminiti wrote:
On Thu, August 26, 2010 12:49 am, Lorenzo Caminiti wrote:
I am trying to use Boost.ScopeExit parameter binding mechanism to implement Boost.LocalFunction. To do so, I need to use some internal ScopeExit code to detect the type of `this` and bind its value to the local function declaration.
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2) Do you know of a workaround for this problem?
I posted a workaround for this a while back (http://lists.boost.org/Archives/boost/2009/03/149540.php) which used type indexing (where the index for typeof(this) is captured outside of a template parameter list) to avoid specifying 'this' in a template parameter list. The mechanics for the solution came from boost.typeof.
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You should be able to use the same type index trick in localfunction. The key definition is the function-style macro BOOST_SCOPE_EXIT_TYPEDEF_TYPEOF_THIS().
Why is this patch defining the following accessors for the ScopeExit local struct?
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I think these are meant to use `this` to access the bound object instead of the local struct object. However, these accessors don't work because `this->` (and `*this`) never calls the overloaded `operator->`:
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Am I not understanding the purpose of the patch's assessors correctly?
At the time the suggest syntax for accessing the enclosing class' this-pointer was the expression
(*this)
So from within the scope-exit you would use (*this) as the object of the enclosing class (rather than plain 'this' which refers to the instance of the scope-exit class). Though contentious, this was my best effort at the time to get the word 'this' into member accesses. Other suggestions IIRC where calling explicit functions such as enclosing_this()-> or this_()-> or having those names as pointer members (i.e. enclosing_this->, or this_->).
The reason for the implicit conversion to reference-to the enclosing instance was to allow passing of (*this) to functions that expected a pointer or reference to the enclosing class.
OK, I understand now. I am using `this_` in my application (Boost.Local) and I will keep that syntax. (FYI, there is a mechanism to use the plain `this` to assess the bound object but it relies on an unsafe `static_cast<>` -- see http://groups.google.com/group/comp.lang.c++.moderated/browse_thread/thread/...) Thanks a lot for the clarification! -- Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/scope-exit-MSVC-error-C2355-this-can-only... Sent from the Boost - Dev mailing list archive at Nabble.com.