Returns a true value iff the watcher is pending, (i.e. it has outstanding
events but its callback has not yet been invoked). As long as a watcher
is pending (but not active) you must not call an init function on it (but
-ev_TYPE_set is safe) and you must make sure the watcher is available to
-libev (e.g. you cnanot free () it).
ev_TYPE_set is safe), you must not change its priority, and you must
+make sure the watcher is available to libev (e.g. you cannot free ()
+it).
If you need to suppress invocation when higher priority events are pending
you need to look at ev_idle watchers, which provide this functionality.
You must not change the priority of a watcher as long as it is active or +pending.
The default priority used by watchers when no priority has been set is
always 0, which is supposed to not be too high and not be too low :).
Setting a priority outside the range of EV_MINPRI to EV_MAXPRI is
fine, as long as you do not mind that the priority value you query might
or might not have been adjusted to be within valid range.
Invoke the watcher with the given loop and revents. Neither
+loop nor revents need to be valid as long as the watcher callback
+can deal with that fact.
If the watcher is pending, this function returns clears its pending status
+and returns its revents bitset (as if its callback was invoked). If the
+watcher isn't pending it does nothing and returns 0.
#include <ev++.h>-
(it is not installed by default). This automatically includes ev.h
-and puts all of its definitions (many of them macros) into the global
-namespace. All C++ specific things are put into the ev namespace.
It should support all the same embedding options as ev.h, most notably
-EV_MULTIPLICITY.
This automatically includes ev.h and puts all of its definitions (many
+of them macros) into the global namespace. All C++ specific things are
+put into the ev namespace. It should support all the same embedding
+options as ev.h, most notably EV_MULTIPLICITY.
Care has been taken to keep the overhead low. The only data member the C++
+classes add (compared to plain C-style watchers) is the event loop pointer
+that the watcher is associated with (or no additional members at all if
+you disable EV_MULTIPLICITY when embedding libev).
Currently, functions, and static and non-static member functions can be +used as callbacks. Other types should be easy to add as long as they only +need one additional pointer for context. If you need support for other +types of functors please contact the author (preferably after implementing +it).
Here is a list of things available in the ev namespace:
ev::READ, ev::WRITE etc.All of those classes have these methods:
The constructor takes a pointer to an object and a method pointer to
-the event handler callback to call in this class. The constructor calls
-ev_init for you, which means you have to call the set method
-before starting it. If you do not specify a loop then the constructor
-automatically associates the default loop with this watcher.
The constructor (optionally) takes an event loop to associate the watcher
+with. If it is omitted, it will use EV_DEFAULT.
The constructor calls ev_init for you, which means you have to call the
+set method before starting it.
It will not set a callback, however: You have to call the templated set
+method to set a callback before you can start the watcher.
(The reason why you have to use a method is a limitation in C++ which does +not allow explicit template arguments for constructors).
The destructor automatically stops the watcher if it is active.
This method sets the callback method to call. The method has to have a
+signature of void (*)(ev_TYPE &, int), it receives the watcher as
+first argument and the revents as second. The object must be given as
+parameter and is stored in the data member of the watcher.
This method synthesizes efficient thunking code to call your method from
+the C callback that libev requires. If your compiler can inline your
+callback (i.e. it is visible to it at the place of the set call and
+your compiler is good :), then the method will be fully inlined into the
+thunking function, making it as fast as a direct C callback.
Example: simple class declaration and watcher initialisation
+ struct myclass
+ {
+ void io_cb (ev::io &w, int revents) { }
+ }
+
+ myclass obj;
+ ev::io iow;
+ iow.set <myclass, &myclass::io_cb> (&obj);
+
+
+ Also sets a callback, but uses a static method or plain function as
+callback. The optional data argument will be stored in the watcher's
+data member and is free for you to use.
The prototype of the function must be void (*)(ev::TYPE &w, int).
See the method-set above for more details.
Example:
+ static void io_cb (ev::io &w, int revents) { }
+ iow.set <io_cb> ();
+
+
+ Associates a different struct ev_loop with this watcher. You can only
@@ -1782,13 +1844,14 @@ do this when the watcher is inactive (and not pending either).
Basically the same as ev_TYPE_set, with the same args. Must be
-called at least once. Unlike the C counterpart, an active watcher gets
-automatically stopped and restarted.
Starts the watcher. Note that there is no loop argument as the
-constructor already takes the loop.
Starts the watcher. Note that there is no loop argument, as the
+constructor already stores the event loop.