QGIS/python/core/additions/fromfunction.py

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# -*- coding: utf-8 -*-
"""
***************************************************************************
fromfunction.py
---------------------
Date : May 2018
Copyright : (C) 2018 by Denis Rouzaud
Email : denis@opengis.ch
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************
"""
from .qgstaskwrapper import QgsTaskWrapper
from qgis._core import QgsTask
@staticmethod
def fromFunction(description, function, *args, on_finished=None, flags=QgsTask.AllFlags, **kwargs):
"""
Creates a new QgsTask task from a python function.
Example:
def calculate(task):
# pretend this is some complex maths and stuff we want
# to run in the background
return 5*6
def calculation_finished(exception, value=None):
if not exception:
iface.messageBar().pushMessage(
'the magic number is {}'.format(value))
else:
iface.messageBar().pushMessage(
str(exception))
task = QgsTask.fromFunction('my task', calculate,
on_finished=calculation_finished)
QgsApplication.taskManager().addTask(task)
"""
assert function
return QgsTaskWrapper(description, flags, function, on_finished, *args, **kwargs)