Classes | Scheduling

Condition : Object

Block the execution of a thread
Source: Condition.sc

Class Methods

Condition.new(test: false)

Create a new instance, set the test variable.

Inherited class methods

Instance Methods

.test

.test = value

Answer whether the condition will block or not (boolean).

.wait

Wait until the condition is true and signalled. This only works in a Routine. This method yields a symbol (\hang), so that the clock doesn't reschedule the Routine.

c = Condition(false); fork { 0.5.wait; "started ...".postln; c.wait;  "... and finished.".postln };
c.test = true;
c.signal;

.hang(value: 'hang')

Wait for value time, regardless of test. This only works in a Routine. This method yields a symbol (\hang), so that the clock doesn't reschedule the Routine.

c = Condition.new; fork { 0.5.wait; "started ...".postln; c.hang;  "... and finished.".postln };
c.unhang;

.signal

If -test is true, reschedule blocked threads.

.unhang

Resume threads.

Inherited instance methods

Examples

(
c = Condition.new(false);

Routine {
    1.wait;
    "waited for 1 second".postln;
    1.wait;
    "waited for another second, now waiting for you ... ".postln;
    c.wait;
    "the condition has stopped waiting.".postln;
    1.wait;
    "waited for another second".postln;
    "waiting for you ... ".postln;
        c.test = false;
        c.wait;
    "the condition has stopped waiting.".postln;
    1.wait;
    "the end".postln;
}.play;
)

// continue
(
c.test = true;
c.signal;
)

// a typical use is a routine that can pause under certain conditions:
(
c = Condition.new;
fork { loop { 1.wait; "going".postln; c.wait } };
)
c.test = true; c.signal;
c.test = false;
// the same, using hang

(
c = Condition.new;

Routine {
    1.wait;
    "waited for 1 second".postln;
    1.wait;
    "waited for another second, now waiting for you ... ".postln;
    c.hang;
    "the condition has stopped waiting.".postln;
    1.wait;
    "waited for another second".postln;
    "waiting for you ... ".postln;
    c.hang;
    "the condition has stopped waiting.".postln;
}.play;
)

// continue
c.unhang;

Waiting for Synths to end (waitForFree) uses a Condition implicitly:

(
SynthDef(\help, { |out|
    var mod = LFNoise2.kr(ExpRand(0.5, 2)) * 0.5;
    var snd =  mod * Blip.ar(Rand(200, 800) * (mod + 1));
    Out.ar(out, snd);
    FreeSelf.kr(mod < 0); // free the synth when amplitude goes below 0.
}).add;
)

(
fork {
    10.do {
        "started a synth".postln;
        Synth(\help).waitForFree;
        "This one ended. Wait a second,  I will start the next one.".postln;
        1.wait;
    };
    "This is it.".postln;
}
);