Re: [Log4cpp-devel] Warning: win32 dll can't export container classes

[Bastiaan B. <Bas...@li...>]

Hmm, that sucks. Any chance of MS fixing this problem soon? Being
limited to only use std::vector in your APIs is ridiculous.
However currrently only getCurrentCategories() is affected. It uses
std::set now, but changing that to std::vector wouldn't hurt very much, 
and may be more efficient as std::vector is the simplest container in
most STL implementations.
Yes, it's an incompatible API change, but 0.3.x is a development branch
anyway. 

Regards,

Bastiaan

PS. The above is not a commitment to keep the log4cpp API MSVC DLL
export clean.

  
On Sun, 2002-06-23 at 10:08, David Resnick wrote:
> I found this out when trying to use Category::getCurrentCategories(),
> which returns std::set<Category*>*. The set I got had 1 good pointer;
> the rest were invalid.
> 
> The problem is detailed by MS in Q168958 "HOWTO: Exporting STL
> Components Inside & Outside of a Class". Here is the key paragraph: 
> 
> "Some STL classes contain nested classes. These classes can not be
> exported. For instance, deque contains a nested class deque::iterator.
> If you export deque, you will get a warning that you must export
> deque::iterator. If you export deque::iterator, you get a warning that
> you must export deque. This is caused by a designed limitation that once
> a template class is instantiated, it can not be re-instantiated and
> exported. The only STL container that can currently be exported is
> vector. The other containers (that is, map, set, queue, list, deque) all
> contain nested classes and cannot be exported."
> 
> So if you want to use methods such as Category::getCurrentCategories(),
> do them in a helper class that is linked as part of the DLL. I added
> what I needed to the SimpleConfigurator (what I needed to do was delete
> previously defined appenders from all categories before reloading a
> config file, so it made sense in any case to put it there.)
> 
> Regards, 
> 
> David Resnick 
> MobileSpear Inc. 
> 
> 
> 
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