08-function-calls.py - Using custom algorithms with python function calls.
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**EventCall** ::

    EventCall(function, *args, occurrences=inf, stopEventsWhenDone=True)

EventCall calls a function, with any number of arguments (\*args) and uses
its return value for the given parameter. The example below use a function
from the random module, *randrange*, with arguments and a user-defined
function, without argument, to create a rising, then falling, amplitude curve.

.. code-block:: python

    import random
    from pyo import *
    
    s = Server().boot()
    
    db = -30
    dir = 1
    
    
    def riseFallAmp():
        "Rises and falls amplitude between -30 and -3 dB, 1 db at the time."
        global db, dir
        db += dir
        if db >= -3:
            dir = -1
        elif db < -30:
            dir = 1
        return db
    
    
    # Midi notes are chosen randomly with a function from the random module,
    # while the amplitude change according to the riseFallAmp function's output.
    e = Events(
        midinote=EventCall(random.randrange, 48, 72, 3),
        beat=1 / 4.0,
        db=EventCall(riseFallAmp),
        attack=0.001,
        decay=0.05,
        sustain=0.5,
        release=0.005,
    ).play()
    
    
    s.gui(locals())