Develop Reference

How to build software like billing software and invoice with modern gui

How do I get started with building software like billing software or invoice maker. I made them
with tkinter but I want them in attractive modern GUI . I don't want them to be web based.
if its not possible with python I can learn other way too. but I don't know how.

I had a very similar issues regarding the aesthetic of a GUI. Perhaps have a look at a good few examples of GUI framework programs here:
https://www.digitaldesignjournal.com/python-gui-framework/
Although they are Tkinter based and probably the same structure overall. It might be a good option for your needs, as I understand.
Please also note that the limitations of GUI aesthetic is also limited in plain tkinter as far as I am concerned.
You can also have a look at tkinter.ttk as follows:
https://www.pythontutorial.net/tkinter/ttk-style/
I have played around a lot with the ttk attributes and it might be a good option to investigate. I find that python is a much easier language to adapt to rather than learn another language solemnly for better GUI aesthetic. (Although important)
I trust that this will help.

I would recommend PyQt. Personally, I find that applications made with PyQt generally have a modern feel. Below you can se an example application I found on a PyQt tutorial:

How to receive input from GUI, apply function, then display?

I wrote a function that receives input as a string, modifies it, and outputs a string. I want to make it so that my non-computer savvy friends can use it, by adding a graphical user interface. I want something very simple: A box where they type in the text, a button that along with hitting "Enter," submits the text, and then a place where it displays the result after my function had modified it. I just want a way to receive input and to write output to a GUI in a way that a regular person can understand. I have no experience with GUIs.
Update
In the end I used XCode to create the GUI and PyObjC to pass the data from GUI to Python in a sort of "frontend-backend" setup.

You may be interested to get a look at http://zetcode.com/
there is a bunch of tutorial about wxPython, PyGTK and PyQt
It should guide you.
Jordi

Does your program have to be python? (as tagged) Your description sounds like a very straightforward task. In that case, have you considered JavaScript + HTML? Your users wouldn't need to download and install anything new, and most people have a good grasp of how to create/use web page forms.
If you're committed to a python implementation: There are a variety of different GUI toolkits (ways of creating the graphical user interface), but which one you choose will depend on how you want your program to look, what operating system you run on, ease of programming, and a variety of factors.
The widgets you describe are fairly simple (text box and button), and you might be able to accomplish your goals using Tk / Tkinter, python's "de facto standard GUI". The advantage of this GUI toolkit is that it's bundled with python on most operating systems, hence (so long as your friends have python installed) they're ready to go. If you don't have experience building complicated installers, then you'll find that users wander off when you require them to install a dozen modules on their own. The TK script would also run on any OS.
Convenience aside, the disadvantage of Tkinter is that Tk is a fairly old and limited framework in the form commonly found with python, and it can be painful to work with for more complicated programs. (some of the online tutorials have typos like mixed case or missing quotation marks) For your task, though, the basic layout and code are pretty simple: see the TkDocs site for a demo that you can adapt.
http://www.tkdocs.com/tutorial/firstexample.html

If you are familier with C# , than you can use IronPython,
just import the Form libraries, make simple form, by putting Lable, Textbox and Button, and refer to that textbox value on Button click. you can get the WOW Gui for Python, with IronPython
Ref : IronPython

Framework for paint program

I've decided to start working on a personal project, attempting to develop a cross platform, MSPaint like app. Oddly enough, I find mspaint is one of the applications I miss the most on Linux or OS X, so I want to try to make something similar. Tuxpaint, mtpaint, gpaint, etc. are all old and inactive and ugly. I don't want to make GIMP, just the basics, similar in features to MS Paint.
I'm thinking of doing it in python with the pygtk toolkit, but I was interested to hear your suggestions. Would C/C++ be a better choice, or even C# (gasp!) with mono? How about using Qt as opposed to GTK, or maybe some other fancy library I don't know about (Please, not FLTK!). I'd be curious to hear your thoughts.
Thanks!

Qt's canvas object (or its newer replacement QGraphicsView) can do pretty cool things. Whether you choose C++ or python is a matter of personal choice, as Qt is supported in both languages. For a simple project like this I'd choose python because killer performance is not much of an issue, and it will be much easier to write.
Another thing to look into is making this app web based with HTML5's canvas object and Javascript. It can be surprisingly robust, and anything that can be put on the cloud is a win in most cases.

If you decide to go with Python (which would be my choice because it's such a simple language), then TkInter is considered the de-facto standard GUI package. That link should send you to some excellent starting references for TkInter, although I also really like Not_a_Golfer's suggestion of an HTML5 web-app.

Short: You can use both, no third party library is guaranteed to be distributed with all major distributions.
Long:
Gtk+ vs. Qt
What do you want incorporate into your application. If it is just selecting a brush, selecting color you could pretty much use any gui toolkit.
If you are going to run it as a web-based tool, Gtk+ has an html5 backend renderer (I don't know about Qt)
A sidenote:
I recommend to use the toolkit's native programming language (gtk+ C, Qt C++) - if you don't, you will suffer from delays with bugfixes, generally more bugs and delayed releases, though for that case it shouldn't really matter.
Everything else boils down to personal preferences and there already exist some questions to tackling that issue.

if you are using qt,you can use QtitanRibbon

Is there a Python library that allows to build user interfaces without writing much code?

I am writing editing front ends in Python since several years now, and I am fed up with micromanaging every UI detail of a window or dialog every single time.
Is there a technology that allows me to, say, specify the relations between a GTK+ Glade-designed interface and the tables and records of an SQLite database to do all the middle man work? It should spare me the work of manually writing event handlers, input evaluators and view updates.
The technologies in question are just examples, but I want to stick with Python as far as possible.

Besides the ones already mentioned I can add:
Kiwi
uxpython
pygtk
treethon
I've never used any of them so have no recommendations but, for what it's worth, I have used at least 2 complex programs built directly on pygtk that worked in both Windows and Linux.
I think Kiwi is the only one of these with baked in support for db (through interface with SQLAlchemy, SQLObject, or Storm) but I would be surprised if you couldn't use one of those ORM's inside any of the other frameworks.

PyQt and its models can automate some of these tasks for you (to some amount off course, e.g. filling widgets with data from a database and handling most of the widgets behaviour, buffering etc.).
If you want a more object-oriented approach to handling SQL you could look into an ORM-oriented solution (for example SQLAlchemy).

Dabo is built on top of wxPython, so you may not prefer it, but it's designed to make it easy to tie a GUI to a database, so I'd recommend you check it out if you haven't already. In particular, it's got good facilities for tying widgets to data, and handling a lot of the common cases of GUI development.

wxGlade may help, although I haven't used it myself so I don't speak from experience.
Boa Constructor apparently has a wxPython GUI builder in it, and there is also PythonCard, though development on these two projects seems to have stalled.

Traits might be a good option for you.
http://code.enthought.com/projects/traits/docs/html/TUIUG/index.html
AS simple as it is to map a UI to an object, it doesn't seem too far fetched to incorporate SQLAlchemy for persistence.

There is a good book on wxPython, "wxPython in Action", which can't be said for some of the other solutions. No knock on the others. I've had success developing with wxPython in the past and it comes with a great set of demo applications with source code from which you can borrow liberally.
The best UI designer I found for wxPython applications is a commercial one, Anthemion DialogBlocks. It's by one of the wxPython programmers and is worth the money. Other solutions for UI design include wxGlade (I found it usable but not featureful) and Boa Constructor (haven't used it). Wing IDE might also have one. Stani's Python Editor bundles wxGlade, I believe. There are a lot of other projects that don't really work or are fairly old.
As far as SQL automation goes, as another answerer says, I'd look at SQL alchemy, but the learning curve for a small application might be too much and you'd be better off just going straight to odbc. The best odbc api is the one used by Django, pyodbc.
It's been a while since I developed with these tools, so there may be something newer for each, but at the time these were definitely the best of breed in my opinion.

I had lots of success with wxPython, but that was some years ago now and there may be better new solutions...

Ok this is an unconventional solution but write yourself a code generator. I have done this several times using Mako. So in my case I auto inspect a table which columns it contains and types and generate classes from that. It's more work upfront but does exactly what you want and is reusable in subsequent projects.

Cross-platform gui toolkit for deploying Python applications

Building on:
http://www.reddit.com/r/Python/comments/7v5ra/whats_your_favorite_gui_toolkit_and_why/
Merits:
1 - ease of design / integration - learning curve
2 - support / availability for *nix, Windows, Mac, extra points for native l&f, support for mobile or web
3 - pythonic API
4 - quality of documentation - I want to do something a bit more complicated, now what?
5 - light weight packaging so it's not necessary to include a full installer (py2exe, py2app would ideally work as-is and not generate a gazillion MBs file)
6 - licensing
7 - others? (specify)
Contenders:
1 - tkinter, as currently supported (as of 2.6, 3.0)
2 - pyttk library
3 - pyGTK
4 - pyQt
5 - wxPython
6 - HTML-CGI via Python-based framework (Django, Turbogears, web.py, Pylons...) or Paste
7 - others? (specify)

Please don't hesitate to expand this answer.
Tkinter
Tkinter is the toolkit that comes with python. That means you already have everything you need to write a GUI. What that also means is that if you choose to distribute your program, most likely everyone else already has what they need to run your program.
Tkinter is mature and stable, and is (at least arguably) quite easy to use.I found it easier to use than wxPython, but obviously that's somewhat subjective.
Tkinter gets a bad rap for looking ugly and out of date. While it's true that it's easy to create ugly GUIs with Tkinter, it's also pretty easy to create nice looking GUIs. Tkinter doesn't hold your hand, but it doesn't much get in the way, either. Tkinter looks best on the Mac and Windows since it uses native widgets there, but it looks OK on linux, too.
The other point about the look of Tkinter is that, for the most part, look isn't as important as people make it out to be. Most applications written with toolkits such as Tkinter, wxPython, PyQT, etc are special-purpose applications. For the types of applications these toolkits are used for, usability trumps looks. If the look of the application is important, it's easy enough to polish up a Tkinter application.
Tkinter has some features that other toolkits don't come close to matching. Variable traces, named fonts, geometry (layout) managers, and the way Tkinter processes events are still the standard to which other toolkits should be judged.
On the downside, Tkinter is a wrapper around a Tcl interpreter that runs inside python. This is mostly invisible to anyone developing with Tkinter, but it sometimes results in error messages that expose this architecture. You'll get an error complaining about a widget with a name like ".1245485.67345" which will make almost no sense to anyone unless you're also familiar with how Tcl/tk works.
Another downside is that Tkinter doesn't have as many pre-built widgets as wxPython. The hierarchical tree widget in Tkinter is a little weak, for example, and there's no built-in table widget. On the other hand, Tkinter's canvas and text widgets are extremely powerful and easy to use. For most types of applications you will write, however, you'll have everything you need. Just don't expect to replicate Microsoft Word or Photoshop with Tkinter.
I don't know what the license is for Tkinter, I assume the same as for python as a whole. Tcl/tk has a BSD-style license.
PyQt
It's build on top of Qt, a C++ framework. It's quite advanced and has some good tools like the Qt Designer to design your applications. You should be aware though, that it doesn't feel like Python 100%, but close to it. The documentation is excellent
This framework is really good. It's being actively developed by Trolltech, who is owned by Nokia. The bindings for Python are developed by Riverbank.
PyQt is available under the GPL license or a commercial one. The price of a riverbank PyQt license is about 400 euro per developer.
Qt is not only a GUI-framework but has a lot of other classes too, one can create an application by just using Qt classes. (Like SQL, networking, scripting, …)
Qt used to emulate GUI elements on every platform but now uses native styles of the platforms (although not native GUI toolkits): see the documentation for Mac OS X and the windows XP style
Packaging is as simple as running py2exe or pyInstaller. The content of my PyQt app looks like this on windows (I have used InnoSetup on top of it for proper installation):
pyticroque.exe PyQt4.QtGui.pyd unicodedata.pyd
MSVCP71.dll PyQt4._qt.pyd unins000.dat
MSVCR71.dll python25.dll unins000.exe
PyQt4.QtCore.pyd sip.pyd _socket.pyd
QT comes with a widget designer and even in recent versions with an IDE to help design Qt software.
PySide
PySide is a LGPL binding to Qt. It's developed by nokia as a replacement for the GPL PyQt.
Although based on a different
technology than the existing
GPL-licensed PyQt bindings, PySide
will initially aim to be
API-compatible with them. In addition
to the PyQt-compatible API, a more
Pythonic API will be provided in the
future.
wxPython
wxPython is a binding for Python using the wxWidgets-Framework. This framework is under the LGPL licence and is developed by the open source community.
What I'm really missing is a good tool to design the interface, they have about 3 but none of them is usable.
One thing I should mention is that I found a bug in the tab-view despite the fact that I didn't use anything advanced. (Only on Mac OS X) I think wxWidgets isn't as polished as Qt.
wxPython is really only about the GUI-classes, there isn't much else.
wxWidgets uses native GUI elements.
An advantage wxPython has over Tkinter is that wxPython has a much larger library of widgets from which to choose from.
Others
I haven't got any experience with other GUI frameworks, maybe someone else has.

I'm just weighing in to say that TKinter sucks. It sadly seems that it is packed with Python because of backwards compatibility.
The documentation is horrible. It looks horrible. I have run into some bizarre bugs that will actually crash Python.

Jython.
Jython is an implementation of the
high-level, dynamic, object-oriented
language Python written in 100% Pure
Java, and seamlessly integrated with
the Java platform. It thus allows you
to run Python on any Java platform.
You can use either Swing, Applet, or other GUI frameworks available to Java platform. See Java Tutorials for Graphical User Interfaces and 2D Graphics. There are plenty of books and documentation such as API reference.
Here's a Hello world Swing application from An Introduction to Jython.
from javax.swing import *
frame = JFrame("Hello Jython")
label = JLabel("Hello Jython!", JLabel.CENTER)
frame.add(label)
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
frame.setSize(300, 300)
frame.show()
Here's a Jython applet by Todd Ditchendorf that demonstrates multi-threaded particle drawing (60 lines).
from __future__ import nested_scopes
import java.lang as lang
import java.util as util
import java.awt as awt
import javax.swing as swing
class Particle:
def __init__(self,initX,initY):
self.x = initX
self.y = initY
self.rng = util.Random()
def move(self):
self.x += self.rng.nextInt(10) - 5
self.y += self.rng.nextInt(20) - 10
def draw(self,g2):
g2.drawRect(self.x,self.y,10,10)
class ParticleCanvas(awt.Canvas):
def __init__(self,newSize):
awt.Canvas.__init__(self,size=(newSize,newSize))
def paint(self,g2):
for p in self.particles:
p.draw(g2)
class ParticleApplet(swing.JApplet):
def init(self):
self.canvas = ParticleCanvas(self.getWidth())
self.contentPane.add(self.canvas)
def start(self):
n = 10
particles = []
for i in range(n):
particles.append(Particle(150,150))
self.canvas.particles = particles
self.threads = []
for i in range(n):
self.threads.append(self.makeThread(particles[i]))
self.threads[i].start()
def makeThread(self,p):
class MyRunnable(lang.Runnable):
def run(this):
try:
while 1:
p.move()
self.canvas.repaint()
lang.Thread.sleep(100)
except lang.InterruptedException:
return
return lang.Thread(MyRunnable())
If you are just interested in drawing lines and circles you can probably cut it down to half.

I would definitely appreciate it if anyone knows of something better than what's commonly discussed; I see to have headaches finding something appropriate...
Qt is great, but PyQt doesn't seem to have the same development resources. It seems to have some clever way to generate bindings, but isn't complete (e.g. PyKDE terminal kpart) and there is a dearth of documentation (as the developers admit). Compatibility with Qt's UI designer is nice.
wxpython - controls aren't as nice looking, widget library isn't as large as KDE.
OpenGL - doesn't even support fonts by default... pygame is okay, but opengl being a state machine is too annoying (object oriented models prevent making the a call in the wrong state).
XUL - neat idea, I wish it worked. The pyxulrunner tutorial didn't work for me, though -- first I had to add the xulrunner /usr/lib path to LD_LIBRARY_PATH, then it still had problems with "from xpcom import components"...
my wishlist for a ui library would be
Python integration (i.e. uses builtins like unicode, modules like threading, and language features like closures)
good intermediate representation (like XUL instead of generating hundreds of lines looking like "listbox91.addChild(label28)")
simple mutlithreaded support (automatic locks or event posting so e.g. elt.setText can be called from any thread; let the designer manage locking with Python locks if necessary)
user-centric features as well - scripting of a sequence of UI events, ability to keybind anything (KDE has dcop, but afaik binding isn't done automatically by the UI library), and intercept events.
potential for a large, easy-to-contribute standard library.
documentation, though if the library was well designed and generated enough interest, this would be a given.
In my experience, html is so much easier to get something good-looking up than UI libraries.
edit - after working with PyQt 4 for a while, it gets the job done for simple UI's. I'm currently not developing for end users, so looks don't matter. The QTextBrowser is very useful for displaying basic HTML tables and generating HTML links.

Pro wxPython
Lots of tutorials
wxGlade as an Editor: not perfect yet, but usable.