[PyQt] PyQt5 and Spyder 3.3.2 Conflict, Beautiful Soup, <kernel died, restarting>

[Gene Ensor]

Kyle,

Many thanks for your response!  However your questions are many levels above my head.  Please note I would be more than happy to run code and report on the output to you or the pseudo forum in an effort to move forward.  Additional information as follows:

On a second run I get:

<kernel died, restarting>
or
<An error occurred while starting the kernel>

Anaconda "Python 3.7.1 64-bit | Qt 5.9.6 | PyQt5 5.9.2 | Windows 10 | Spyder 3.3.2

Spyder>help>dependencies

IPython >=4.0     :  7.2.0 (OK)
cython >=0.21     :  0.29.2 (OK)
jedi >=0.9.0      :  0.13.2 (OK)
matplotlib >=2.0.0:  3.0.2 (OK)
nbconvert >=4.0   :  5.4.0 (OK)
numpy >=1.7       :  1.15.4 (OK)
pandas >=0.13.1   :  0.23.4 (OK)
pycodestyle >=2.3 :  2.4.0 (OK)
pyflakes >=0.6.0  :  2.0.0 (OK)
pygments >=2.0    :  2.3.1 (OK)
pylint >=0.25     :  2.2.2 (OK)
qtconsole >=4.2.0 :  4.4.3 (OK)
rope >=0.9.4      :  0.11.0 (OK)
sphinx >=0.6.6    :  1.8.2 (OK)
sympy >=0.7.3     :  1.3 (OK)

Thanks again!

Gene

-----Original Message-----
From: Kyle Altendorf <sda at fstab.net> 
Sent: Saturday, March 23, 2019 7:59 PM
To: pyqt at riverbankcomputing.com; Gene Ensor <g_ensor at hotmail.com>; pyqt at riverbankcomputing.com
Subject: Re: [PyQt] PyQt5 and Spyder 3.3.2 Conflict, Beautiful Soup, <An error occurred while starting the kernel>

Have you verified in those cases that the app exit is being called?  If you fail out because of an exception it won't be.  I would really manage the app outside your class.  (Does Qt really force you to inherit here?). Then you can try/finally to make sure it gets exited even after a python exception.  Or even make yourself a context manager.

Cheers,
-kyle

On March 23, 2019 9:28:13 PM EDT, Gene Ensor <g_ensor at hotmail.com> wrote:
>Team,
>
>Per
>
>https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithu
>b.com%2Fspyder-ide%2Fspyder%2Fwiki%2FHow-to-run-PyQt-applications-withi
>n-Spyder&data=02%7C01%7C%7Cefe8a2de6a6a456bbd4708d6affc3ef3%7C84df9
>e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636889895249156064&sdata=kKve
>zNdJY%2BYL2%2F4Yjyq%2BQLdN%2BgtR%2BVyRRwK8vADUi0I%3D&reserved=0
>
>I believe I have the following problem:
>
>"The most common problem when running a PyQt multiple times inside 
>Spyder is that a QApplication instance remains in the namespace of the 
>IPython console kernel after the first run. In other words, when you 
>try to re-run your application, you already have a QApplication 
>instance initialized."
>
>Hence when ran a second time I get "An error occurred while starting 
>the kernel".  However I am not skilled enough to update the below code 
>to behave correctly my environment.
>
>Anaconda "Python 3.7.1 64-bit | Qt 5.9.6 | PyQt5 5.9.2 | Windows 10 | 
>Spyder 3.3.2
>
>Can you assist?  Thanks!
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>import sys
>from PyQt5.QtWebEngineWidgets import QWebEnginePage from 
>PyQt5.QtWidgets import QApplication, QDialog from PyQt5.QtCore import 
>QUrl, QCoreApplication
>
>import bs4 as bs
>import urllib.request
>
>
>class Page(QWebEnginePage):
>    def __init__(self, url):
>#       PyQt5 has the "minimal" platform plugin.
>#       To use it, modify the argv passed to QApplication to include
>#       ['-platform', 'minimal'].
>        self.app = QApplication(sys.argv)
>        QWebEnginePage.__init__(self)
>        self.html = ''
>        self.loadFinished.connect(self._on_load_finished)
>        self.load(QUrl(url))
>        self.app.exec_()
>
>    def _on_load_finished(self):
>        self.html = self.toHtml(self.Callable)
>        print('Load finished')
>
>    def Callable(self, html_str):
>        self.html = html_str
>        self.app.quit()
>
>
>def main():
>    page = Page('https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpythonprogramming.net%2Fparsememcparseface%2F&data=02%7C01%7C%7Cefe8a2de6a6a456bbd4708d6affc3ef3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636889895249156064&sdata=uuqunuxYJs1xxShwscoSbBVf%2Bb1Su6A2l5zn%2FhCBsK8%3D&reserved=0')
>    soup = bs.BeautifulSoup(page.html, 'html.parser')
>    js_test = soup.find('p', class_='jstest')
>    print(js_test.text)    #fixed
>    # output should be "Look at you shinin!"
>if __name__ == '__main__': main()
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~