CODEWITHSUNDEEP
iphonec++objective-ciostemplates
konran
konran

Reputation: 588

Mixing ObjC and C++ with C++ template classes in more than one source

I'm just thinking of porting some old C++ sources held in my archive to iOS thus supplying a ObjC GUI, using wrappers for some C++ stuff and leave the important data working stuff within the C++ code. So, the problem is that the old sources come from Win32 MFC thus using CString class for strings and I want to replace that with Joe O'Leary's CStdString which is a C++ template class that will do it just fine ... but:

I have to use the string class definition along with a big bunch of different C++ sources and so each of them will include the CStdString template on their own. Normally I would write a wrapper for the whole string class, but better if I needn't.

Will I have a problem with instantiation of strings in the different sources? Could it make a problem to pass a templated string from one source to another? In fact I don't know if the compiler generates the code for a template only once or multiple times having the fact that the same instantiation type is used for the template.

Can you fill some light into this?

Thanks...

Upvotes: 0

Views: 421

Answers (2)

Goles
Goles

Reputation: 11799

I agree with CString, as long as you stay with std::string or some other multi-platform string implementation for C++ you are not going to face any issues ( even boost works on iOS ).

I've been integrating C++/Obj-C for about two years now so you can be sure that keeping model classes in C++ ( even with heavily templated code ), is not a problem. I would advice you to do what you could do best with Obj-C in Obj-C though... ( avoiding being a hammer developer :) )

Good luck!

Upvotes: 0

AJG85
AJG85

Reputation: 16197

MFC and CString may only work properly on Windows OS so they aren't good candidates to be putting in any kind of library that will be potentially used by a platform other than windows.

I'm not familiar with Joe O'Leary's CStdString classes but I'd recommend using std::string as much as possible and char* with "extern C" exports and wrapping functions for use outside of C++ land as the c-style string is more easily compatible with other languages that may need to call into your C++ library.

As far as templates all the variations are generated at compile time and then the correct implementation is chosen at run time as far as I know. However your problem will most likely be in translation from one kind of string to another which may require you to create some middle layer or wrapper to marshal from string type of one language to another.

Upvotes: 1

Related Questions