Sawa SAW4

How to use metaclass to implement Singleton in Python

First, you need to know that instance of metaclass is class,
just like : an instance of class is object, they have similar idea

Then you need to change the rule of metaclass of your class, to let it only allow create the instance once only.
If the class instance is not None (instance is existed), then return the instance, else create new instance of class.

One more important thing, metaclass is type
class is the instance of type (metaclass)
the origin of class is type (I may say that)

Linux connect to Windows Printer through Samba

The first thing: Install and launch service

Install stuffs
sudo pacman -S samba smbclient cups
Launch required services
sudo systemctl enable smbd nmbd winbindd //nmbd may not required, it used to resolve netbios name
sudo systemctl start smbd nmbd winbindd

Config your printer in CUPS

Go to localhost:631, enter remote printer the address

Tips: How to start Anaconda Natvigator - Plasma Application Menu

Plasma Application Menu provide flexible, user-friendly interface for modifing apps menu, user can run shell script, python script, lua script, binary by one click.
However Plasma Applicaiton Menu do not pass any environment variable by default, you need to do if by yourself :(
Here is a example for launching Anaconda Natvigator.

source /home/user/.zshrc && zsh -c "/home/user/anaconda3/bin/anaconda-navigator"

Aria2c WebUI - How to make DirectURL permanent

As mention by author, DircetURL's setting should be set in the file configuration.js
But after many times I tried, its not worked as expected.
So, just have a look to the code ... to see what's happening during WebUI initialization?
Finally I found a temporary solution. In the file js/services/rpc/rpc.js :

...
...
  if (['http', 'https'].indexOf(uri.protocol()) != -1 && uri.host() != 'localhost') {
 configurations.push({

Tips: How to change disqus link color?

Add the following style to your head tag

<head>
...
...
  <style> 
 #disqus_thread a {

Customize Chart.js Radar Chart

In dataset, you can see:

backgroundColor: "rgba(128,128,128,0.2)",   /** bgcolor inside the grid */
borderColor: "#4099FF",                     /** color of the link */
pointBackgroundColor: "#4099FF",            /** color of circle point */
pointBorderColor: "#fff",                   /** color of circle's border */
pointHoverBackgroundColor: "#4099FF"
pointHoverBorderColor: "#4099FF"

	void MainInterface::ShowPathToCurr() {
	TreeNodeButton* NodeButton = qobject_cast<TreeNodeButton*>(sender());
	QPropertyAnimation *a;
	int i = 1;
	for (Node* curr = NodeButton->get_localref(); !curr->activated; curr=curr->prev,++i){
	QGraphicsOpacityEffect *eff = new QGraphicsOpacityEffect(this);
	a= new QPropertyAnimation(eff, "opacity");
	curr->Widgetptr->setGraphicsEffect(eff);
	curr->Widgetptr->setGraphicsEffect(eff);
	a->setDuration(1000+i*500);

	from functools import wraps
	...
	...
	class MainInterface(QMainWindow):
	...
	...
	# Reusble Exception checking funciton (For file manager, open file)
	def fm_handle_stripe(f):
	def wrapper(args, *kwargs):
	try:


	# Create a new Qmenu
	self.sqlcfg_menu = QtWidgets.QMenu(self)

	# First item here, index 0
	icon = QIcon(os.path.join(self.path, "image/File.png"))
	self.sqlcfg_menu.addAction(icon, 'my.cnf', lambda: self.sqlConfMan('my.cnf'))

	# Second item, index 1
	self.sqlcfg_menu.addSeparator()

	--[[ Gtk.Revealer widget hiding animation with Lua & lgi

	intro: revealer use to hide and show widgets with different transitions
	demo: create a toolbar, hide/show by using a button(named:testbutton)

	--]]

	-- Import the module that you need
	local lgi = require ('lgi')
	local Gtk = lgi.Gtk