\& #include <ev++.h>
.Ve
.PP
-(it is not installed by default). This automatically includes \fIev.h\fR
-and puts all of its definitions (many of them macros) into the global
-namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace.
-.PP
-It should support all the same embedding options as \fIev.h\fR, most notably
-\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
+This automatically includes \fIev.h\fR and puts all of its definitions (many
+of them macros) into the global namespace. All \*(C+ specific things are
+put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
+options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
+.PP
+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 \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
+.PP
+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).
.PP
Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
.Sp
All of those classes have these methods:
.RS 4
-.IP "ev::TYPE::TYPE (object *, object::method *)" 4
-.IX Item "ev::TYPE::TYPE (object *, object::method *)"
+.IP "ev::TYPE::TYPE ()" 4
+.IX Item "ev::TYPE::TYPE ()"
.PD 0
-.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4
-.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)"
+.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
+.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
.IP "ev::TYPE::~TYPE" 4
.IX Item "ev::TYPE::~TYPE"
.PD
-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
-\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR 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 \f(CW\*(C`EV_DEFAULT\*(C'\fR.
+.Sp
+The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
+\&\f(CW\*(C`set\*(C'\fR method before starting it.
+.Sp
+It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
+method to set a callback before you can start the watcher.
+.Sp
+(The reason why you have to use a method is a limitation in \*(C+ which does
+not allow explicit template arguments for constructors).
.Sp
The destructor automatically stops the watcher if it is active.
+.IP "w\->set<class, &class::method> (object *)" 4
+.IX Item "w->set<class, &class::method> (object *)"
+This method sets the callback method to call. The method has to have a
+signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
+first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
+parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
+.Sp
+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 \f(CW\*(C`set\*(C'\fR 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.
+.Sp
+Example: simple class declaration and watcher initialisation
+.Sp
+.Vb 4
+\& struct myclass
+\& {
+\& void io_cb (ev::io &w, int revents) { }
+\& }
+.Ve
+.Sp
+.Vb 3
+\& myclass obj;
+\& ev::io iow;
+\& iow.set <myclass, &myclass::io_cb> (&obj);
+.Ve
+.IP "w\->set (void (*function)(watcher &w, int), void *data = 0)" 4
+.IX Item "w->set (void (*function)(watcher &w, int), void *data = 0)"
+Also sets a callback, but uses a static method or plain function as
+callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
+\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
+.Sp
+See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
.IP "w\->set (struct ev_loop *)" 4
.IX Item "w->set (struct ev_loop *)"
Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
.IP "w\->set ([args])" 4
.IX Item "w->set ([args])"
Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
-called at least once. Unlike the C counterpart, an active watcher gets
-automatically stopped and restarted.
+called at least once. Unlike the C counterpart, an active watcher gets
+automatically stopped and restarted when reconfiguring it with this
+method.
.IP "w\->start ()" 4
.IX Item "w->start ()"
-Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the
-constructor already takes the loop.
+Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
+constructor already stores the event loop.
.IP "w\->stop ()" 4
.IX Item "w->stop ()"
Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
\& }
.Ve
.PP
-.Vb 6
+.Vb 4
\& myclass::myclass (int fd)
-\& : io (this, &myclass::io_cb),
-\& idle (this, &myclass::idle_cb)
\& {
+\& io .set <myclass, &myclass::io_cb > (this);
+\& idle.set <myclass, &myclass::idle_cb> (this);
+.Ve
+.PP
+.Vb 2
\& io.start (fd, ev::READ);
\& }
.Ve
In this section the complexities of (many of) the algorithms used inside
libev will be explained. For complexity discussions about backends see the
documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
+.Sp
+All of the following are about amortised time: If an array needs to be
+extended, libev needs to realloc and move the whole array, but this
+happens asymptotically never with higher number of elements, so O(1) might
+mean it might do a lengthy realloc operation in rare cases, but on average
+it is much faster and asymptotically approaches constant time.
.RS 4
.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
as only the relative motion in the event queue has to be paid for.
.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
-These just add the watcher into an array or at the head of a list. If
-the array needs to be extended libev needs to realloc and move the whole
-array, but this happen asymptotically less and less with more watchers,
-thus amortised O(1).
-.IP "Stopping check/prepare/idle watchers: O(1)" 4
-.IX Item "Stopping check/prepare/idle watchers: O(1)"
-.PD 0
+These just add the watcher into an array or at the head of a list.
+=item Stopping check/prepare/idle watchers: O(1)
.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
-.PD
These watchers are stored in lists then need to be walked to find the
correct watcher to remove. The lists are usually short (you don't usually
have many watchers waiting for the same fd or signal).
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