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great idea. radically simplify the method callbacks

master
Marc Alexander Lehmann 14 years ago
parent
commit
97ec2832ad
  1. 35
      ev++.h

35
ev++.h

@ -8,39 +8,26 @@ namespace ev {
template<class watcher>
class callback
{
struct object { };
struct klass; // it is vital that this is never defined
void *obj;
void (object::*meth)(watcher &, int);
/* a proxy is a kind of recipe on how to call a specific class method */
struct proxy_base {
virtual void call (void *obj, void (object::*meth)(watcher &, int), watcher &w, int) const = 0;
};
template<class O1, class O2>
struct proxy : proxy_base {
virtual void call (void *obj, void (object::*meth)(watcher &, int), watcher &w, int e) const
{
((reinterpret_cast<O1 *>(obj)) ->* (reinterpret_cast<void (O2::*)(watcher &, int)>(meth)))
(w, e);
}
};
proxy_base *prxy;
klass *o;
void (klass::*m)(watcher &, int);
public:
template<class O1, class O2>
explicit callback (O1 *object, void (O2::*method)(watcher &, int))
{
static proxy<O1,O2> p;
obj = reinterpret_cast<void *>(object);
meth = reinterpret_cast<void (object::*)(watcher &, int)>(method);
prxy = &p;
o = reinterpret_cast<klass *>(object);
m = reinterpret_cast<void (klass::*)(watcher &, int)>(method);
}
void call (watcher *w, int e) const
// this works because a standards-compliant C++ compiler
// basically can't help it: it doesn't have the knowledge
// required to miscompile (klass is not defined anywhere
// and nothing is known about the constructor arguments) :)
void call (watcher *w, int revents)
{
return prxy->call (obj, meth, *w, e);
(o->*m) (*w, revents);
}
};

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