[PD] [Pd] Compile external with C++ compiler?

Mon May 7 12:48:00 CEST 2012

Hi Ed,

Sorry for the delay, these emails got filtered out of my inbox for some
reason :(

You make the object in C, compile it and then build your patch in pd
> vanilla + the object.
> Then in the xcode object you just call the setup function for the object,
> the source code for which gets included in the xcode project.
> That's all I know. I'm not responsible for the Xcode/C++ of this app, only
> the Pd patch and Pd objects, so there may be more to it. It's quite simple
> though, my developer colleague tells me.
> Don't forget, C is a subset of C++!

Yep, this is what I'm doing. The issue is that to call C++ code in the C
external I need to compile it with a C++ compile, therefore I change the
source code extension to .mm (objective-c++). Now when I do this Xcode goes
all weird about class_addmethod(), which is maybe a namespace issue - I'm
not sure. But it means I can't add any methods in the external.

The solution I used was to write a C wrapper for the C++ library, it's a
bit annoying as any function I want to use has to be declared in the
wrapper, but it works so I can't complain. Maybe your dev guy might have a
solution? :)

Glad to see others using Pd on iOS/Android!

Cheers,
Joe

On 27 April 2012 21:54, Ed Kelly <morph_2016 at yahoo.co.uk> wrote:

> It's really easy actually.
>
> You make the object in C, compile it and then build your patch in pd
> vanilla + the object.
> Then in the xcode object you just call the setup function for the object,
> the source code for which gets included in the xcode project.
> That's all I know. I'm not responsible for the Xcode/C++ of this app, only
> the Pd patch and Pd objects, so there may be more to it. It's quite simple
> though, my developer colleague tells me.
> Don't forget, C is a subset of C++!
>
> Ed
>
> Gemnotes-0.1alpha: Live music notation for Pure Data
> http://sharktracks.co.uk/
>    ------------------------------
> *From:* Joe White <white.joe4 at gmail.com>
> *To:* Charles Henry <czhenry at gmail.com>
> *Cc:* pd-list <pd-list at iem.at>
> *Sent:* Friday, 27 April 2012, 9:56
> *Subject:* Re: [PD] [Pd] Compile external with C++ compiler?
>
> Hi Charles,
>
> Thanks for replying!
>
> I don't believe it's a problem calling C functions, you just have to
> declare them with 'extern "C"' to avoid name mangling (I think??).
>
> The issue is, when I want to use C++ I have to switch the implementation
> file to ".mm", which is a Objective-C++ file. As soon as I do this Xcode
> starts complaining about 'class_addmethod()' in my setup function. The
> weird thing is that it only applies to 'class_addmethod()'. For example,
> 'class_addbang()', 'class_new()' all work fine.
>
> It seems like it's an issue only with this function, and it looks like class_addMethod
> is already a function used by Objective-C <https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html> I
> think maybe there's some namespace issues, but I have no idea how to
> resolve this.
>
> wrote wrapper functions to export a C-callable public interface to C++
> functions.
>
>
> Yep, this is what I'm doing now. A bit annoying because I was so close :)
>
> Thanks for your help!
>
> Cheers,
> Joe
>
> On 27 April 2012 04:10, Charles Henry <czhenry at gmail.com> wrote:
>
> Hi guys
>
> The part that I don't get is how to call C functions from C++? I don't
> think I've even tried that before.  Have you?
> Joe: I've built externals that just call C++ functions that I declared
> with extern "C" or wrote wrapper functions to export a C-callable
> public interface to C++ functions.  Best suggestion I've got is to
> identify which functions you've got are going to be public and which
> ones are private and plan out how you're going to declare them.
>
> Chuck
>
> On 4/26/12, Ed Kelly <morph_2016 at yahoo.co.uk> wrote:
> > Hi Joe,
> >
> > Have you thought of using ofxPd?
> >
> > I'm involved in the creation of an app for the iPhone right now, and
> we're
> > using ofxPd from Dan Wilcox:
> > https://github.com/danomatika/ofxPd
> > Since Openframeworks is a bunch of C++ wrappers for various libraries,
> ofxPd
> > adds Pd to the libraries that you can work with in C++.
> > Then you can call the setup function within the xcode build, and your
> object
> > will work in libpd (i.e. ofxPd) in the app environment.
> > Bear in mind that Apple do not like GnuGPL licensed stuff, so I've
> created
> > BSD licensed versions of some of my own Pd externals for this project.
> >
> >
> > And the app works. We're in the final stages now, so I'll post to the
> list
> > when it's complete!
> > Best,
> > Ed
> >
> >
> > Gemnotes-0.1alpha: Live music notation for Pure Data
> > http://sharktracks.co.uk/
> >
> >
> > ________________________________
> >  From: Joe White <white.joe4 at gmail.com>
> > To: pd-list <pd-list at iem.at>
> > Sent: Thursday, 26 April 2012, 16:51
> > Subject: [PD] [Pd] Compile external with C++ compiler?
> >
> >
> > Hi all,
> >
> > Thought I might as well ask this here because you guys know everything :)
> >
> > I'm writing an external to be built into an iOS app that's running Pd.
> The
> > catch is I need to interface with a C++ library within the external.
> >
> > The external builds and runs fine if I'm using the C compiler (in Xcode)
> but
> > I can't access the C++ library functions. If I switch it to compile in
> C++
> > (by changing the objective-c file from .m to .mm) then I can use the C++
> > library functions but it complains that it can't find 'class_addmethod'
> >
> >                           'No matching function for call to
> > 'class_addmethod'
> >
> > I've tried declaring the setup function as C code like Katja explains on
> her
> > site:
> >                           extern "C" void external_tilde_setup(void) { }
> > But that still didn't seem to work. I was also going through the list and
> > found this thread but I'm not sure if it's the right approach. Plus I'm
> more
> > of an audio guy than programmer :)
> >
> > Any ideas would be much appreciated.
> >
> > Thanks,
> > Joe
> > --
> > Follow me on Twitter @diplojocus
> >
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