Wow. That is a really awesome trick there. Props to you!!
I wish Boost was easier to split apart so I didn't need to drag around
40MB of headers for just one feature…
Chris Meyer wrote:
Don't listen to these C++ naysayers... we use it all the time very
successfully.
An easy way of reference counting using Obj-C++, I've used the boost
libraries with boost::intrusive_ptr and these definitions:
// file.h
namespace boost
{
void intrusive_ptr_add_ref( id object );
void intrusive_ptr_release( id object );
}
// file.m
namespace boost
{
void intrusive_ptr_add_ref( id object )
{
[object retain];
}
void intrusive_ptr_release( id object )
{
[object release];
}
}
Then you can do things like:
MyObjCObject *my_object = [[[MyObjCObject alloc] init] autorelease];
boost::intrusive_ptr< MyObjCObject> my_object_ptr = my_object;
Now my_object_ptr can be safely stored in C++ classes, used in other
classes such as
stl::vector< boost::intrusive_ptr< MyObjCObject> > my_list;
etc.
Hope this helps.
On Thu, Mar 20, 2008 at 9:40 AM, Jeremy <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Thanks for the input guys, I really appreciate the help.
I do have a lot of C++ code that I would like to use and put behind a
Cocoa front end, so I think that using Objective C++ classes as
wrapper classes around my C++ classes is the route I would like to
take.
Anyone have an example of such a wrapper class so I can get an idea of
what is the preferred methodology?
I'm guessing that you create an Objective C++ class with a member
variable that is a C++ class and then mirror the methods from the C++
class?
I'm worried that I'll still end up having to import the header file
for my C++ class in my Objective C source file though, which caused a
lot of compile errors previously.
On Mar 20, 2008, at 12:32 PM, John Stiles wrote:
> Without starting a religious war, I have to disagree with this.
>
> ObjC++ is probably a bad idea if you are a novice programmer in
> general, but I think it also has some really good things going for
> it, and having written huge amounts of ObjC++ code, I think it's
> perfectly straightforward to use. It is by far your best bet for
> writing cross-platform code that uses a native Cocoa front end.
>
>
> Rob Napier wrote:
>>
>> On Wed, Mar 19, 2008 at 4:12 PM, Jeremy <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
>>
>>> Hi.
>>>
>>> I am just starting to learn Cocoa and would like to use
standard C
>>> ++
>>> classes from my Objective C/C++ classes.
>>>
>> You really don't. You think you do (probably because you know C++),
>> but then you enter the crazy messed up world of Objective-C++ and
>> discover that you really wish you hadn't. A bit of an
overstatement,
>> yes, but really I'd recommend against using ObjC++ unless you have
>> existing C++ code that you have to bridge to, and then it's
best used
>> just to wrap the C++ classes so that ObjC can deal with them. Learn
>> Cocoa in pure ObjC.
>>
>> ObjC and C++ have very different models for managing memory, types,
>> pointers and well, just about everything. Memory management in
>> particular is a real hassle. ObjC++ strips away the safety nets
from
>> both ObjC and C++ because now you have to track two very different
>> ways of managing memory (retain counting versus ref variables for
>> instance).
>>
>>
>>> Is there any known documentation on how to do this, or does
anyone
>>> have any pointers?
>>>
>>> I tried creating a new object of my C++ class and calling a
>>> method on
>>> it in a .m file and received a bunch of errors (including new not
>>> being found).
>>>
>>> I then changed my .m file to a .mm file and all of the errors
went
>>> away except for one:
>>> "cannot find interface declaration for 'MyClass'"
>>>
>> This probably means that ObjC expects there to be an ObjC class
>> called
>> MyClass (rather than a C++ class called MyClass; they're completely
>> unrelated class structures). I suspect that you accidentally put
>> "@class MyClass" somewhere rather than "class MyClass", or possibly
>> wrote "@interface MyClass" somewhere. Alternately, you failed
to put
>> "class MyClass" above the declaration of m_pMemberVariable and
so the
>> compiler assumed MyClass was an ObjC class (this is less likely
since
>> you should have gotten a compiler error elsewhere for that error).
>>
>> I strongly recommend naming your ObjC and ObjC++ classes
differently.
>> I typically name the ObjC++ classes ending in "Wrapper" but that's
>> because I only ever use these classes to wrap existing C++ classes
>> defined in separate C++-only projects.
>>
>> Also, make sure that you're working in the right namespace. You may
>> need to say "new myNamespace::MyClass" here.
>>
>> ObjC++ is deep magic. It is not a good place to learn Cocoa. It
is a
>> useful tool once you know Cocoa and need to integrate it at key
>> points
>> with C++.
>>
>> -Rob
>>
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