Posts about python (old posts, page 23)

2009-03-01 23:38

PyQt by example (Session 1)

I am finally publishing my LatinoWare 2008 tutorial, in revised and expanded form. It will probably be a 10-part series, and here is session 1

2009-03-01 10:43

Using assistant from PyQt

The uRSSus doc is slowly growing, so I hooked assistant to the UI. Not difficult, but I have not seen it elsewhere.

Here's how:

Assume the "Handbook action" is called action_Handbook. Set window.assistant to None in __init__.

def on_action_Handbook_triggered(self, i=None):
    if i==None: return

    if not self.assistant or \
       not self.assistant.poll()==None:

        cmd="assistant -enableRemoteControl -collectionFile %s"%helpcoll
    self.assistant.stdin.write("SetSource qthelp://urssus/doc/handbook.html\n")

And that's it. Now I ned to figure out context help.

2009-02-24 21:42

Rawdog is flexible: using Mako templates

I am using rawdog for Planeta PyAr and I am very happy with it. One thing I really didn't like was the templating.

Why? It's basically undocumented, it looks ugly and it doesn't support template inheritance, which in this case is very useful, because I am actually doing two very similar planets: 1 2.

So, since I saw a plugin to use Vellum templates, which means the templating is pluggable, why not use my favourite templating library (Mako) instead?

It turns out to be very easy to do!

Just put this in your plugins folder and start using Mako templates (yes, the planet's config and stuff is in github. Why not?).

# -*- coding: utf-8 -*-
import rawdoglib.plugins

from mako.template import Template
from mako.lookup import TemplateLookup
from mako import exceptions

class MakoPlugin:
    def __init__(self):
        self.lookup = TemplateLookup(directories=['.'],\

    def fill_template(self,template, bits, result):
        return False

p = MakoPlugin()

Yup, 20 lines of code!

2009-02-23 11:22

rst2qhc 0.2: the insomnia release

Today I woke up at 6AM. I had nothing to do until 9, but I woke up and couldn't sleep again.

So, what can I do? I hacked rst2qhc a bit more :-D

Since this is a small project, it is quickly approaching feature complete status (there is really only so much this thing can do).

So, what's new?

  • Passing options to rst2html, so you can do things like set stylesheets.
  • Support for a manifest file, so you can list what files should be embedded in the helpfile.
  • Fixed project support. Now you can optionally ask rst2qhc to create a qhcp file that will build your document.
  • Better, more complete example that displays most features.

I have only one thing left in my TODO, which is calling the HTML writer via API instead of via system() because that way there is no need to define the keyword role in the document, and I can add syntax highlighting via pygments.

Since I now do have work to do, I will just release 0.2 now ;-)

You can get it from the usual place:

And here's a sample of the input/output:


2009-02-22 03:18

Now you, too can create Qt Help Files painlessly

I decided to add a manual for uRSSus. Since it's a Qt app, I checked how to do one of those neat help files, like the ones that come with Qt apps.

It turns out it's not so simple to create one of those.

You need to create your help in one or more HTML files, then create a XML file that describes what each file is, references for each section, and references for each keyword you want in the index.

For any real-life-size document, that's going to be incredibly annoying.

So, I took my usual escape route when I don't want to do grunt work on docs: Docutils.

Specifically, I wrote rst2qhc which takes one (or more) restructured text files, and creates a nice and clean Qt Help Project file from them, including section titles, references and keywords, which you mark on the text using the 'keyword' role.

What does this mean? Let me be graphical:


The one on the right is nice to read. The one on the left is nice to write. The arrow in the middle is rst2qhc :-)

And here's how the generated qhp file looks for a trivial outline of a manual (and the reason why I don't want to do this manually ;-):

<?xml version="1.0" encoding="UTF-8"?>
<QtHelpProject version="1.0">
    <customFilter name="Unknown">
            <section title="The uRSSus Handbook" ref="manual.html">
                <section title="Introduction" ref="manual.html#introduction"/>
                <section title="Quick Start" ref="manual.html#quick-start"/>
                <section title="Configuration" ref="manual.html#configuration"/>
                <section title="Credits and License" ref="manual.html#credits-and-license"/>
                <keyword name="what can you" ref="manual.html#what-can-you-do-using-urssus"/>
                <keyword name="quick" ref="manual.html#quick-start"/>
                <keyword name="main window" ref="manual.html#the-main-window"/>

Also, as a bonus, you can create PDF, LaTeX, HTML and ODT files from the same source (heck, you can create freaking man pages).

2009-02-21 20:19

Planeta PyAr, or how to generate multiple planets with rawdog

I just finished implementing my first public planet, Planeta PyAr using rawdog. It contains the blogs of members of Python Argentina

To avoid the classical argument about whether this is "the planet of people in PyAr" or "posta about python from people in PyAr", I decided to hack rawdog into producing both.

I didn't want to have two separate rawdog configurations, so I started looking at plugins.

The basis was the selectfeeds plugin and the rss plugin.

Then I merged selectfeeds into rss to make things simpler.

Here is my hacked version which takes the selectfeed argument and uses only those feeds when creating the HTML, FOAF, OPML and RSS files.

The bad side of this is that selectfeed requires you post the feed URLs all in one line!

With just a couple dozen blogs in the planet, that means several hundred characters. And then when you decide to change one URL... ick.

So, I wrote a tiny script to take separate feed files and create separate config files,

Now, I create a feeds-full file with the non-python-specific feeds in rawdog format:

# Feeds full

# Anthony Lenton
feed 20m
# Rivendel
feed 20m
# Facundo Batista
feed 20m

And the same for a feeds-python:

# Feeds solo python

# Anthony Lenton
feed 20m
# Rivendel
# No tiene RSS solo python
# Facundo Batista
# No tiene RSS solo python
# Gabriel Patiño
feed 20m

Put all the common configurations in config-base.

And produces a config, a config-full and a config-python.

Then run rawdog like this:

cd ~/.rawdog ; LANG=es_ES rawdog -c config-full -w ; LANG=es_ES rawdog -c config-python -w

And that's it, two planets for the cost of one and a half.I wonder why other planets don't provide this.

2009-02-17 12:26

uRSSus 0.2.12 released!


Announcing release 0.2.12 or uRSSus a RSS/Atom aggregator.

This release fixes the big crashy updater bug in 0.2.11, and makes some minor improvements, like nicer date display, and a xdg resource installer.

2009-02-13 22:23

Indeed screw all gui builders... for java!

Reading DZone I ran into an interesting post titled Screw all GUI builders which advocates dropping all GUI builders and instead coding your UI by hand.

I always advocate using Qt Designer instead of coding by hand, so I wanted to see, even it's talking about Java, I thought, "why don't I feel that way"?

My conclusion? I don't see it because in PyQt we are just lucky because our tools don't suck quite as much.

It gives several arguments:

  • You don't know how exactly the generated code works. You don't need to. You start not to care and GUI application development becomes a process of drawing and adding simple event handlers here and there.

To that, my reaction was yes, indeed I don't care, as long as it works, which it has 99.99% of the time. When it didn't, I did understand the generated code, though.

The reason for this will be more obvious once you see the code in both cases, I think.

  • Most GUI builders force you to use single class for single window, so generated classes tend to have thousands of lines of code.

Hmmm... I really don't know what this means in context, but that's just my java ignorance. OTOH, yes, one class per window, but almost never thousands of lines of code.

For example, the UI for uRSSus main window is quite complex, and it is only 530 lines of code. Here's how it looks, so you see it's not a trivial window:

urssus23 * Most GUI builders don't want you to modify the generated code. And if you do, they either break or rewrite your code.

Indeed Designer's code is not meant to be modified. That's what inheritance is there for. Overload whatever you want changed. Maybe this is easier in PyQt because Python is more dynamic than Java? Not sure.

  • GUI builders force you to use an IDE, mostly one you started coding with. So if you start with NetBeans, you most likely be forced to stay with it for the whole project.

Just not true for Designer. I can see how that would suck, though.

  • The generated code is far from being optimal. It's not resize-friendly, not dynamic enough, it has many hard-coded values, refactoring is most likely impossible, because builder would not allow that.

Designer does generate resize-friendly dialogs if you use it correctly. The hard-coded values are runtime-editable, refactoring is pretty simple (take whatever you want, create a widget with it?)

And since I wanted to compare apples to apples...

Here is his dialog, done via PyQt and Designer:


No, I didn't bother inserting text in the dialog so it loks the same ;-)

The "close" button closes the window, the URL opens in your system browser.

The text widget actually supports a subset of HTML, so there is a valid HTML document there, instead of just plain text.

Also, another thing is ... Designer's (or rather pyuic's) generated code is straightorward stuff.

Here's the code, which I think is roughly equivalent to his, only it's just 123 LOC, instead of 286 (his generated version) or 279 (his hand-made version). And I didn't delete the comments.

If I were doing this for real, all widgets would have descriptive names instead of PushButton1 and whatever.

Also, it's i18n-ready, unlike the Java versions, unless I missed something.

You can also get hawkscope.ui from this site to play with, it's done with Designer from Qt 4.4.

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'hawkscope.ui'
# Created: Fri Feb 13 22:39:47 2009
#      by: PyQt4 UI code generator 4.4.4
# WARNING! All changes made in this file will be lost!

from PyQt4 import QtCore, QtGui

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.resize(444, 357)
        self.verticalLayout_2 = QtGui.QVBoxLayout(Dialog)
        self.horizontalLayout_2 = QtGui.QHBoxLayout()
        self.label_2 = QtGui.QLabel(Dialog)
        self.verticalLayout = QtGui.QVBoxLayout()
        self.label_3 = QtGui.QLabel(Dialog)
        font = QtGui.QFont()
        self.label_4 = QtGui.QLabel(Dialog)
        self.gridLayout = QtGui.QGridLayout()
        self.label_5 = QtGui.QLabel(Dialog)
        font = QtGui.QFont()
        self.gridLayout.addWidget(self.label_5, 0, 0, 1, 1)
        self.label_10 = QtGui.QLabel(Dialog)
        self.gridLayout.addWidget(self.label_10, 0, 1, 1, 1)
        self.label_9 = QtGui.QLabel(Dialog)
        font = QtGui.QFont()
        self.gridLayout.addWidget(self.label_9, 1, 0, 1, 1)
        self.label_8 = QtGui.QLabel(Dialog)
        self.gridLayout.addWidget(self.label_8, 1, 1, 1, 1)
        self.label_7 = QtGui.QLabel(Dialog)
        font = QtGui.QFont()
        self.gridLayout.addWidget(self.label_7, 2, 0, 1, 1)
        self.label_6 = QtGui.QLabel(Dialog)
        self.gridLayout.addWidget(self.label_6, 2, 1, 1, 1)
        self.label = QtGui.QLabel(Dialog)
        font = QtGui.QFont()
        self.textBrowser = QtGui.QTextBrowser(Dialog)
        self.horizontalLayout = QtGui.QHBoxLayout()
        spacerItem = QtGui.QSpacerItem(40, 20, QtGui.QSizePolicy.Expanding, QtGui.QSizePolicy.Minimum)
        self.pushButton = QtGui.QPushButton(Dialog)
        self.pushButton_2 = QtGui.QPushButton(Dialog)

        QtCore.QObject.connect(self.pushButton_2, QtCore.SIGNAL("clicked()"), Dialog.accept)

    def retranslateUi(self, Dialog):
        Dialog.setWindowTitle(QtGui.QApplication.translate("Dialog", "Dialog", None, QtGui.QApplication.UnicodeUTF8))
        self.label_3.setText(QtGui.QApplication.translate("Dialog", "Hawkscope", None, QtGui.QApplication.UnicodeUTF8))
        self.label_4.setText(QtGui.QApplication.translate("Dialog", "Access anything with single click!", None, QtGui.QApplication.UnicodeUTF8))
        self.label_5.setText(QtGui.QApplication.translate("Dialog", "Version:", None, QtGui.QApplication.UnicodeUTF8))
        self.label_10.setText(QtGui.QApplication.translate("Dialog", "0.4.1", None, QtGui.QApplication.UnicodeUTF8))
        self.label_9.setText(QtGui.QApplication.translate("Dialog", "Released:", None, QtGui.QApplication.UnicodeUTF8))
        self.label_8.setText(QtGui.QApplication.translate("Dialog", "2009-02-06", None, QtGui.QApplication.UnicodeUTF8))
        self.label_7.setText(QtGui.QApplication.translate("Dialog", "Homepage:", None, QtGui.QApplication.UnicodeUTF8))
        self.label_6.setText(QtGui.QApplication.translate("Dialog", "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"\">\n"
"<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\n"
"p, li { white-space: pre-wrap; }\n"
"</style></head><body style=\" font-family:\'Droid Sans\'; font-size:8pt; font-weight:400; font-style:normal;\">\n"
"<p style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"><a href=\"\"><span style=\" text-decoration: underline; color:#3c7dbe;\"></span></a></p></body></html>", None, QtGui.QApplication.UnicodeUTF8))
        self.label.setText(QtGui.QApplication.translate("Dialog", "Environment", None, QtGui.QApplication.UnicodeUTF8))
        self.textBrowser.setHtml(QtGui.QApplication.translate("Dialog", "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"\">\n"
"<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\n"
"p, li { white-space: pre-wrap; }\n"
"</style></head><body style=\" font-family:\'Droid Sans\'; font-size:8pt; font-weight:400; font-style:normal;\">\n"
"<p style=\" margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\">Text goes here</p>\n"
"<p style=\"-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\"></p></body></html>", None, QtGui.QApplication.UnicodeUTF8))
        self.pushButton.setText(QtGui.QApplication.translate("Dialog", "C&opy To Clipboard", None, QtGui.QApplication.UnicodeUTF8))
        self.pushButton.setShortcut(QtGui.QApplication.translate("Dialog", "Alt+O", None, QtGui.QApplication.UnicodeUTF8))
        self.pushButton_2.setText(QtGui.QApplication.translate("Dialog", "&Close", None, QtGui.QApplication.UnicodeUTF8))

2009-02-13 13:37

Counting unread items is HARD

I mean, if google can get it wrong, I have an excuse, right?


See how at the same time you see:

  • At the left: "All items (8)"
  • At the top-center: "8 new items"
  • In the tree: 8 items
  • In the list: 14 new items

Each of those numbers can get out of sync with each other if you do something the "wrong" way.

But what the heck, it seems as of r678 urssus does it right. The list of unread posts even updates when you have it open adding the new posts in the right places without disturbing you, and keeping the right numbers everywhere, AFAICS!


So here, in uRSSUs:

  • 13 unread articles in the "Unread Articles" item
  • 13 in "All Feeds"
  • 13 adding each folder
  • 13 in the article list

Sadly, this is all post-0.2.11 release.

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