Python 3.7.3 : Using the inotify.

About this tool you can read here:
inotify functionality is available from the Linux kernel and allows you to register one or more directories for watching, and to simply block and wait for notification events.

[mythcat@desk ~]$ pip3 install inotify --user
...
Successfully installed inotify-0.2.10 nose-1.3.7

Let's test it and see how this can be load it:

[mythcat@desk ~]$ python3
Python 3.7.4 (default, Jul  9 2019, 16:32:37) 
[GCC 9.1.1 20190503 (Red Hat 9.1.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import inotify
>>> from inotify import *
>>> print(dir(inotify))
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', 
'__path__', '__spec__', '__version__']
>>> import inotify.adapters
>>> print(dir(inotify))
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', 
'__path__', '__spec__', '__version__', 'adapters', 'calls', 'constants', 'library']
>>> print(dir(inotify.adapters))
['EINTR', 'EventTimeoutException', 'Inotify', 'InotifyTree', 'InotifyTrees', 'TerminalEventException', 
'_BaseTree', '_DEFAULT_EPOLL_BLOCK_DURATION_S', '_DEFAULT_TERMINAL_EVENTS', '_HEADER_STRUCT_FORMAT', 
'_INOTIFY_EVENT', '_IS_DEBUG', '_LOGGER', '_STRUCT_HEADER_LENGTH', '__builtins__', '__cached__', '__doc__',
 '__file__', '__loader__', '__name__', '__package__', '__spec__', 'collections', 'inotify', 'logging', 'os',
 'select', 'struct', 'time']
>>> import inotify.calls
>>> print(dir(inotify.calls))
['InotifyError', '_LIB', '_LOGGER', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', 
'__name__', '__package__', '__spec__', '_check_nonnegative', '_check_nonzero', '_check_zero', 'ctypes', 
'errno', 'inotify', 'inotify_add_watch', 'inotify_init', 'inotify_rm_watch', 'logging']
>>> import inotify.constants
>>> print(dir(inotify.constants))
['IN_ACCESS', 'IN_ALL_EVENTS', 'IN_ATTRIB', 'IN_CLOEXEC', 'IN_CLOSE', 'IN_CLOSE_NOWRITE', 'IN_CLOSE_WRITE', 
'IN_CREATE', 'IN_DELETE', 'IN_DELETE_SELF', 'IN_DONT_FOLLOW', 'IN_IGNORED', 'IN_ISDIR', 'IN_MASK_ADD', 
'IN_MODIFY', 'IN_MOVE', 'IN_MOVED_FROM', 'IN_MOVED_TO', 'IN_MOVE_SELF', 'IN_NONBLOCK', 'IN_ONESHOT', 
'IN_ONLYDIR', 'IN_OPEN', 'IN_Q_OVERFLOW', 'IN_UNMOUNT', 'MASK_LOOKUP', '__builtins__', '__cached__', 
'__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__']
>>> import inotify.library
>>> print(dir(inotify.library))
['_FILEPATH', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', 
'__spec__',
 'ctypes', 'instance']

Let's test it with a simple watch issue for a file named test_file.
First, let create this file:

[mythcat@desk ~]$ touch /tmp/test_file
[mythcat@desk ~]$ ll /tmp/test_file 
-rw-rw-r--. 1 mythcat mythcat 0 Aug 22 13:54 /tmp/test_file

Now, I can use the next script to watch on it:

import inotify.adapters
def notif_tmp():
    adapter_tmp = inotify.adapters.Inotify()

    adapter_tmp.add_watch('/tmp')

    with open('/tmp/test_file', 'w'):
        pass

    events = adapter_tmp.event_gen(yield_nones=False, timeout_s=1)
    events = list(events)

    print(events)
if __name__ == '__main__':
    notif_tmp()

The result is this:

$ python3 notif.py 
[(_INOTIFY_EVENT(wd=1, mask=2, cookie=0, len=16), ['IN_MODIFY'], '/tmp', 'test_file'), 
(_INOTIFY_EVENT(wd=1, mask=32, cookie=0, len=16), ['IN_OPEN'], '/tmp', 'test_file'), 
(_INOTIFY_EVENT(wd=1, mask=8, cookie=0, len=16), ['IN_CLOSE_WRITE'], '/tmp', 'test_file')]

If remove this file the result will be this:

$ python3 notif.py 
[(_INOTIFY_EVENT(wd=1, mask=256, cookie=0, len=16), ['IN_CREATE'], '/tmp', 'test_file'), 
(_INOTIFY_EVENT(wd=1, mask=32, cookie=0, len=16), ['IN_OPEN'], '/tmp', 'test_file'), 
(_INOTIFY_EVENT(wd=1, mask=8, cookie=0, len=16), ['IN_CLOSE_WRITE'], '/tmp', 'test_file')]

Let's test another example:

import inotify.adapters
import logging
_LOGGER = logging.getLogger(__name__)
def test():
    i = inotify.adapters.Inotify()
    i.add_watch('/tmp')

    try:
        for event in i.event_gen():
            if event is not None:
                (header, type_names, path, filename) = event
                _LOGGER.info("WD=(%d) MASK=(%d) COOKIE=(%d) LEN=(%d) MASK->NAMES=%s "
                             "FILENAME=[%s]",
                             header.wd, header.mask, header.cookie, header.len, type_names,
                             filename)
                print(header, type_names, path, filename)
    finally:
        i.remove_watch('/tmp')

if __name__ == '__main__':
    test()

If you run this and will try to edit with vim editor the /tmp/text.txt file the output will be this:

$ python3 notif_002.py
_INOTIFY_EVENT(wd=1, mask=32, cookie=0, len=16) ['IN_OPEN'] /tmp text.txt
_INOTIFY_EVENT(wd=1, mask=256, cookie=0, len=16) ['IN_CREATE'] /tmp .text.txt.swp
_INOTIFY_EVENT(wd=1, mask=32, cookie=0, len=16) ['IN_OPEN'] /tmp .text.txt.swp
...

If you want to use many paths then use this:

    paths = [
        '/tmp',
    ]
    i = Inotify(paths=paths)

This module is not well documented but can be successfully used for certain tasks.

Python Qt5 : contextMenu example.

A context menu is a menu in a graphical user interface (GUI) that appears upon user interaction, such as a right-click mouse operation.
I create the default application and I use QMenu to create this context menu with New, Open and Quit.

from PyQt5 import QtGui
from PyQt5.QtWidgets import QApplication, QMainWindow, QMenu
import sys


class Window(QMainWindow):
    def __init__(self):
        super().__init__()
        self.title = "PyQt5 Context Menu"
        self.top = 100
        self.left = 100
        self.width = 640
        self.height = 480
        self.InitWindow()


    def InitWindow(self):
        self.setWindowIcon(QtGui.QIcon("icon.png"))
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)
        self.show()

    def contextMenuEvent(self, event):
        contextMenu = QMenu(self)
        new_Act = contextMenu.addAction("New")
        open_Act = contextMenu.addAction("Open")
        quit_Act = contextMenu.addAction("Quit")
        action = contextMenu.exec_(self.mapToGlobal(event.pos()))
        if action == quit_Act:
            self.close()


App = QApplication(sys.argv)
window = Window()
sys.exit(App.exec())

Python Qt5 : the QTimer class.

I haven't written about PyQt5 in a while and today I decided to add a short tutorial on this python module.
The QTimer class is a high-level programming interface for timers and provides repetitive and single-shot timers.
I this example I call a method every second with these lines:

        self.timer = QTimer()
        self.timer.timeout.connect(self.handleTimer)
        self.timer.start(1000)

The timer is stop when the value check by handleTimer has value 100 else the ProgressBar increment the default value with 1.
The full source of code is this:

import sys
from PyQt5.QtCore import QTimer
from PyQt5.QtWidgets import QApplication, QMainWindow, QProgressBar
from PyQt5.QtCore import Qt

class QTimer_ProgressBar(QMainWindow):

    def __init__(self):
        super().__init__()

        self.pbar = QProgressBar(self)
        self.pbar.setGeometry(30, 70,400, 50)
        self.pbar.setValue(0)

        self.setWindowTitle("QTimer Progressbar")
        self.setGeometry(64,64,640,480)
        self.show()

        self.timer = QTimer()
        self.timer.timeout.connect(self.handleTimer)
        self.timer.start(1000)

    def handleTimer(self):
        value = self.pbar.value()
        if value < 100:
            value = value + 1
            self.pbar.setValue(value)
        else:
            self.timer.stop()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = QTimer_ProgressBar()
    sys.exit(app.exec_())

You can also use it like this:

def Qt():
    try:
        # Do things
    finally:
        QTimer.singleShot(5000, Qt)

Qt()

Python 3.7.3 : Using the flask - part 014.

Today I worked on YouTube search with flask and Google A.P.I. project.
The source code is simple to understand and you can test any A.P.I. from google using this way.
I created a new Google project with YouTube A.P.I. version 3 and with the A.P.I. key.
I use this key to connect with flask python module.
I used the isodate python module.
You can see the source code on my GitHub repo named flask_yt.
The result is this:

Python 3.7.3 : Using the flask - part 013.

Flask uses Jinga2 template engine.
The Jinga2 template engine uses the following delimiters for escaping from HTML.
We can use this:

• {% ... %} for Statements
• {{ ... }} for Expressions to print to the template output
• {# ... #} for Comments not included in the template output
• # ... ## for Line Statements

The documentation webpage comes with all information about how can be used.
I create a new HTML5 file named layout.html and I will use this like an example:

{% if current_user.is_authenticated %}
...
{% else %}
...
{% endif %}

This file can be add into another file like this:

{% extends "layout.html" %}
{% block content %}
...
{% endblock content %}

For example, my about.html webpage comes with this source code:

{% extends "layout.html" %}
{% block content %}
    
About Page
{% endblock content %}

The routes.py this webpage will have this call:

@app.route("/about")
def about():
    return render_template('about.html', title='About')

In this way, I will add more HTML5 files to the project.