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python - PyQt QThreadPool运行函数如何传递参数

转载 作者:太空宇宙 更新时间:2023-11-04 01:49:37 32 4
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关于此代码的问题:Multithreading PyQt applications with QThreadPool

从下面的代码中,如何将附加参数从 oh_no 函数传递给 execute_this_fn

如果我像参数一样直接传递:

worker = Worker(self.execute_this_fn(arg1, arg2))

并像往常一样接受:

def execute_this_fn(self, progress_callback, a ,b):

我收到一个错误:

result = self.fn(*self.args, **self.kwargs) TypeError: execute_this_fn() got multiple values for argument 'progress_callback'

甚至有评论说“给任何参数和参数设置路径以运行函数”,但正确的语法是什么?

文章中的可执行代码:

from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *

import time
import traceback, sys


class WorkerSignals(QObject):
'''
Defines the signals available from a running worker thread.

Supported signals are:

finished
No data

error
`tuple` (exctype, value, traceback.format_exc() )

result
`object` data returned from processing, anything

progress
`int` indicating % progress

'''
finished = pyqtSignal()
error = pyqtSignal(tuple)
result = pyqtSignal(object)
progress = pyqtSignal(int)


class Worker(QRunnable):
'''
Worker thread

Inherits from QRunnable to handler worker thread setup, signals and wrap-up.

:param callback: The function callback to run on this worker thread. Supplied args and
kwargs will be passed through to the runner.
:type callback: function
:param args: Arguments to pass to the callback function
:param kwargs: Keywords to pass to the callback function

'''

def __init__(self, fn, *args, **kwargs):
super(Worker, self).__init__()

# Store constructor arguments (re-used for processing)
self.fn = fn
self.args = args
self.kwargs = kwargs
self.signals = WorkerSignals()

# Add the callback to our kwargs
self.kwargs['progress_callback'] = self.signals.progress

@pyqtSlot()
def run(self):
'''
Initialise the runner function with passed args, kwargs.
'''

# Retrieve args/kwargs here; and fire processing using them
try:
result = self.fn(*self.args, **self.kwargs)
except:
traceback.print_exc()
exctype, value = sys.exc_info()[:2]
self.signals.error.emit((exctype, value, traceback.format_exc()))
else:
self.signals.result.emit(result) # Return the result of the processing
finally:
self.signals.finished.emit() # Done



class MainWindow(QMainWindow):


def __init__(self, *args, **kwargs):
super(MainWindow, self).__init__(*args, **kwargs)

self.counter = 0

layout = QVBoxLayout()

self.l = QLabel("Start")
b = QPushButton("DANGER!")
b.pressed.connect(self.oh_no)

layout.addWidget(self.l)
layout.addWidget(b)

w = QWidget()
w.setLayout(layout)

self.setCentralWidget(w)

self.show()

self.threadpool = QThreadPool()
print("Multithreading with maximum %d threads" % self.threadpool.maxThreadCount())

self.timer = QTimer()
self.timer.setInterval(1000)
self.timer.timeout.connect(self.recurring_timer)
self.timer.start()

def progress_fn(self, n):
print("%d%% done" % n)

def execute_this_fn(self, progress_callback):
for n in range(0, 5):
time.sleep(1)
progress_callback.emit(n*100/4)

return "Done."

def print_output(self, s):
print(s)

def thread_complete(self):
print("THREAD COMPLETE!")

def oh_no(self):
# Pass the function to execute
worker = Worker(self.execute_this_fn) # Any other args, kwargs are passed to the run function
worker.signals.result.connect(self.print_output)
worker.signals.finished.connect(self.thread_complete)
worker.signals.progress.connect(self.progress_fn)

# Execute
self.threadpool.start(worker)


def recurring_timer(self):
self.counter +=1
self.l.setText("Counter: %d" % self.counter)


app = QApplication([])
window = MainWindow()
app.exec_()

最佳答案

如果您查看 Worker 类的文档,我们会看到它指示了如何建立附加参数:

class Worker(QRunnable):
"""
Worker thread

Inherits from QRunnable to handler worker thread setup, signals and wrap-up.

:param callback: The function callback to run on this worker thread. Supplied args and
kwargs will be passed through to the runner.
:type callback: function
:param args: Arguments to pass to the callback function
:param kwargs: Keywords to pass to the callback function
# ...

在您的情况下,您必须更改为:

worker = Worker(self.execute_this_fn, arg1, arg2)

另一方面,如果观察到源代码的以下部分:

# ...
self.kwargs["progress_callback"] = self.signals.progress
# ...

从中可以看出 progress_callback 是必须在 args 之后的 kwargs 的一部分,因此您必须将代码更改为:

def execute_this_fn(self, a, b, progress_callback):

关于python - PyQt QThreadPool运行函数如何传递参数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58327821/

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