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<copyright> TOO Timer.
Written by <a href="mailto:tiggr@ics.ele.tue.nl">Pieter J. Schoenmakers</a>
Copyright (C) 1997 Pieter J. Schoenmakers.
This file is part of TOM. TOM is distributed under the terms of the
TOM License, a copy of which can be found in the TOM distribution; see
the file LICENSE.
<id>$Id: Timer.t,v 1.7 1998/01/05 01:16:51 tiggr Exp $</id>
</copyright>
<doc> Instances of the {Timer} class provide, in conjunction with the
{RunLoop}, event scheduling functionality. {Timer} objects can fire
once or repeatedly.
Because the trigger time of a {Timer} can change, in case of repeated
firing, a {Timer} is not a {Date}: a {Timer} represents a moment in
time like a {Date}, but a {Date} is assumed to be constant. </doc>
implementation class
Timer: HeapElement
instance (id)
withInterval double secs
invocation Invocation invocation
repeats: boolean repeats_p = NO
pre
secs > 0.0 || (!repeats_p && !secs)
{
= [[self alloc]
initWithFireTime [Date relativeTimeIntervalSinceNow] + secs
invocation invocation period: repeats_p ? secs : 0.0];
}
end;
implementation instance
Timer
{
<doc> The next (relative) moment in time we will fire. </doc>
public double fire_time;
<doc> The repetition period. This is 0.0 for a single-shot timer. </doc>
public double period;
<doc> The invocation to fire when we do. </doc>
Invocation invocation;
}
<doc> Designated initializer. If the time {d} lies in the past, the timer
will fire as soon as possible. </doc>
id (self)
initWithFireTime double d
invocation Invocation i
period: double p = 0.0
pre
p >= 0.0
{
(fire_time, invocation, period) = (d, i, p);
}
void
fire
{
[invocation fire];
if (period != 0.0)
{
fire_time += period;
[[RunLoop current] add_timer self];
}
}
OutputStream (s)
writeFields OutputStream s
{
s = [s print (" fire_time=", fire_time)];
}
/********** RunLoop interaction **********/
<doc> Cancel this timer with the current {RunLoop}. It must be scheduled
with that {RunLoop}. </doc>
void
cancel
pre
[self scheduled]
{
[[RunLoop current] remove_timer self];
}
<doc> Schedule this timer with the current {RunLoop}. The timer may not
already be scheduled. </doc>
void
schedule
pre
![self scheduled]
{
[[RunLoop current] add_timer self];
}
<doc> Return whether this timer is currently scheduled. </doc>
boolean
scheduled
{
= heap_index != 0;
}
/******************** Comparable ********************/
<doc><h4>Comparable</h4></doc>
int
compare id other
{
double ft = [other fire_time];
= fire_time > ft ? 1 : fire_time < ft ? -1 : 0;
}
end;
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