CODEWITHSUNDEEP
pythonpython-3.xpyqtpyqt5qtimer
Devenepali
Devenepali

Reputation: 157

Problem calling fucntion with lambda along with QTimer.singleShot

I tried to called a function with delay time with of help of QTimer.singleShot function but is not yielding any output.

from PyQt5.QtCore import QTimer

list1=[1,2,3,4,5]
delay = 2500

def calling_func():
    if list1:
        list_item = list1.pop()
        QTimer.singleShot(delay, lambda: target_func(list_item))


def target_func(list_item):
    print("fid= ",list_item)
    QTimer.singleShot(delay, calling_func)


calling_func()

I am expecting to output list_item value one by one in target_func but the function is not being called.

Upvotes: 1

Views: 1017

Answers (1)

eyllanesc
eyllanesc

Reputation: 243897

The asynchronous elements of Qt such as signals and timers use the eventloop for their execution, in your case there are none so it fails. The solution is to create a Q{Core, Gui, }Application:

from PyQt5.QtCore import QCoreApplication, QTimer

list1=[1,2,3,4,5]
delay = 2500

def calling_func():
    if list1:
        list_item = list1.pop()
        QTimer.singleShot(delay, lambda: target_func(list_item))


def target_func(list_item):
    print("fid= ",list_item)
    QTimer.singleShot(delay, calling_func)

app = QCoreApplication([])
calling_func()
app.exec_()

Upvotes: 2

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