{{tag>Brouillon Python}}

= Python - callback2

https://pythonexamples.org/python-callback-function/

<code python>
def callbackFunc(s):
    print('Length of the text file is : ', s)

def printFileLength(path, callback):
    f = open(path, "r")
    length = len(f.read())
    f.close()
    callback(length)

if __name__ == '__main__':
    printFileLength("sample.txt", callbackFunc)
</code>	

<code python>
def callbackFunc1(s):
    print('Callback Function 1: Length of the text file is : ', s)

def callbackFunc2(s):
    print('Callback Function 2: Length of the text file is : ', s)

def printFileLength(path, callback):
    f = open(path, "r")
    length = len(f.read())
    f.close()
    callback(length)

if __name__ == '__main__':
    printFileLength("sample.txt", callbackFunc1)
    printFileLength("sample.txt", callbackFunc2)
</code>


---------

https://www.localsolver.com/docs/last/technicalfeatures/callbacks.html

<code python>
class CallbackExample:
    def __init__(self):
        self.last_best_value = 0
        self.last_best_running_time = 0

    def my_callback(self, ls, cb_type):
        stats = ls.statistics
        obj = ls.model.objectives[0]
        if obj.value > self.last_best_value:
            self.last_best_running_time = stats.running_time
            self.last_best_value = obj.value
        if stats.running_time - self.last_best_running_time > 5:
            print(">>>>>>> No improvement during 5 seconds: resolution is stopped")
            ls.stop()
        else:
            print(">>>>>> Objective %d" % obj.value)

ls = localsolver.LocalSolver()
cb = CallbackExample()
ls.add_callback(localsolver.LSCallbackType.TIME_TICKED, cb.my_callback)
</code>

---------

https://www.askpython.com/python/built-in-methods/callback-functions-in-python

<code python>
def called(n):
    return n[0]*n[1]
 
def caller(func, n):
    return func(n)
 
#tuple
num = (8, 5)
 
ans = caller(called, num)
 
print("Multiplication =", ans)
</code>

---------

https://www.delftstack.com/howto/python/python-callback-function/

<code python>
def Func_CallBack(c):
    print("File Length : ", c)


def File_Len(filepath, callback):
    i = open(filepath, "r")
    file_length = len(i.read())
    i.close()
    callback(file_length)


if __name__ == "__main__":
    File_Length("randomfile.txt", Func_CallBack)
</code>

---------------

https://stackoverflow.com/questions/40843039/how-can-i-write-a-simple-callback-function

<code python>
def callback(n):
    print("Sum = {}".format(n))

def main(a, b, _callback = None):
    print("adding {} + {}".format(a, b))
    if _callback:
        _callback(a+b)

main(1, 2, callback)
</code>


-------

https://www.ionos.fr/digitalguide/sites-internet/developpement-web/quest-ce-quun-callback/

<code python>
def get_square(val):
    return val ** 2

def caller(func, val):
    return func(val)

caller(get_square, 5)
</code>