Re: [gtkmm] g_module

[ERDI Gergo <cactus cactus rulez org>]

On 2 Aug 2002, Murray Cumming wrote:

> However, if you need something to find C++ symbols at runtime rather
> than C symbols then life will probably be more difficult due to C++ name
> mangling. If that's what you need then I suggest that you look at
> libglademm 0.x (The GNOME 1.4 version in sourceforge). The original
> author seemed to have some solution for this. I haven't put that stuff
> into libglademm2 yet because I have not had time to understand it.

I have a pretty simple solution for this:

class PluggableBase
{
public:
	virtual ~PluggableBase () {};
	virtual void foo () = 0;
	virtual void bar () = 0;

	typedef PluggableBase* (*creator_t) (const T1& param1, int param2);
};


Then in a plugin .cc:

class PluggableImplA: public PluggableBase
{
	//...
};

extern "C" PluggableBase* create_pluggable (const T1& param1, int param2)
{
    return new PluggableImplA (param1, param2);
}

The important part is that create_pluggable should be linked as a C
function to avoid name mangling.

Usage with the C API of g_module is very simple (using the 1.2 API here):

    GModule *plugin_handle = g_module_open ("foo.so", G_MODULE_BIND_LAZY);
    chkerror(g_module_error());

    gpointer creator_func_p;
    if (!g_module_symbol (plugin_handle, "create_pluggable", &creator_func_p))
        chkerror(g_module_error());

    PluggableBase::creator_t create_func =
	static_cast<PluggableBase::creator_t> creator_func_p;
    
    PluggableBase *plugin_obj = creator_func (P1, 10);

    return plugin_obj;



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