returning std::string/std::list from dll

Question

Short question.

I just got a dll I\'m supposed to interface with. Dll uses crt from msvcr90D.dll (notice D), and returns std::strings, std::lists, and boost::shared_

Answer 1

I'm not sure about "anything that could call new/delete" - this can be managed by careful use of shared pointer equivalents with appropriate allocators/deleter functions.

However in general, I wouldn't pass templates across DLL boundaries - the implementation of the template class ends up in both sides of the interface which means you can both be using a different implementation. Bad things will happen unless you can always guarantee that your entire set of binaries is all built with the same toolchain.

When I need this sort of functionality I often use a virtual interface class across the boundary. You can then provide wrappers for std::string, list etc. that allow you to safely use them via the interface. You can then control allocation etc. using your implementation, or using a shared_ptr.

Having said all this, the one thing I do use in my DLL interfaces is shared_ptr, as it's too useful not to. I haven't yet had any problems, but everything is built with the same toolchain. I'm waiting for this to bite me, as no doubt it will. See this previous question: Using shared_ptr in dll-interfaces