Robert Basic's blog

Archives for November, 2010

Passing arguments to custom slots in PyQt

by Robert Basic on November 30, 2010.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

While hacking on ape, I came to a situation where I need to pass some arguments to a custom defined slot. The slot is being called from different signals, one where the argument is passed by PyQt itself and a second one where I need to programmatically pass the argument to the slot.

First I tried with something like:

action = QAction("My action", parent)
action.triggered.connect(my_slot(my_argument))

which ended in an error: TypeError: connect() slot argument should be a callable or a signal, not ‘NoneType’

After a bit of poking around I passed a lambda function to the connect() method:

action = QAction("My action", parent)
action.triggered.connect(lambda arg=my_argument: my_slot(arg))

Works like a charm.

Also this is my first try to use github gists as a way to embed/highlight code. Hope it’ll work out.

Happy hackin’!

Tags: ape, lambda, pyqt, python, signals, slots.
Categories: Programming.

Connecting signals and slots with PyQt - the new style

by Robert Basic on November 09, 2010.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

While working on ape I had a problem with figuring out how to properly connect a signal to a slot, where the signal is emitted by a QTreeView widget. As this is not my first app with python and pyqt, I was doing something like (this is, btw, the “old style”):

self.connect(widget, SIGNAL("emitted_signal()"), self.my_slot)

but it simply didn’t work. Nothing happened. I was trying all different of connect/signal/slot combinations but everything was just dead silent. Google gave only pretty much old posts talking about QT3. Then I figured that, because the QTreeView is “sitting” inside a QDockWidget, maybe that dock widget thingy is somehow intercepting/taking over the signals. Nope. Wth? Wtf is going on? Current pyqt version is (on my machine) 4.6. Last time I used pyqt it was something like 4.2 or 4.3. Something must’ve been changed in the mean time. Off to the pyqt docs I go (btw, I use the official QT docs, the C++ version, there isn’t really a big difference from pyqt): PyQt reference, chapter 7 - “New-style Signal and Slot Support”. A-ha! They changed it! Here is an example of the “new style”:

widget.emmited_signal.connect(self.my_slot)

Oh my, isn’t that just beautiful?! Much more readable and simpler, for me at least. And it works! Yay! The QTreeView signals are happily connected to slots, thus, I’m happy too.

A few paragraphs later, turns out that the “old style” isn’t thrown out, it should still work. Why it didn’t work for me escapes me at the moment, but honestly, I don’t really care as long as the new style is working.

Happy hackin’!

Tags: ape, pyqt, python, signals, slots.
Categories: Development, Programming.

ape is a PHP editor

by Robert Basic on November 06, 2010.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

A week ago I started working on a simple editor/IDE for PHP called ape. That’s my weak try on creating a reverse acronym as ape stands for - ape is a PHP editor. This is kind of an introductory post into the whole developing process of it, as my intention is to blog about it a bit more :)

Why?

First, to answer the question everyone is giving me when I mention I’m writing ape:
“Why the hell do you do that (to yourself)?”

Programming is fun. Programming is interesting. Programming makes me learn new things. I like having fun and I do this to learn more about programming and having even more fun. I’m writing web applications each and every day, so writing a desktop app requires a different way of thinking and leaving my “comfort zone” (altho, I’m quite comfortable in front of the keyboard hackin’ away code). ape is written in python and pyqt, but again, it’s not about the language used, for me it is about programming.

The idea

Netbeans is my main IDE for quite some time now and I love it. I know my way around vim, too. But, netbeans has too many features for my taste - I use SVN, git, (on rare occasions I write them) run unit tests from the console. As for vim, maybe I just don’t get it enough, but I feel less productive with it. Debugging PHP apps ends up var_dump-ing things all over the place. So, basically what I want/need from an editor is grouping files into projects, regex search/replace, code coloring & completion and, of course, file editing.

I plan to write a feature a day. On my personal projects I usually want to push out as much code as I can during one day as I’m highly motivated, but this time want to try a different approach. So far I didn’t got far, figured out syntax highlighting, opening files from a file browser widget thingy and things like that, but more on that in other posts.

If anyone wants to take a look, the source code is up on github. It is licensed under GNU GPL v2, as pyqt is licensed under it and I don’t want to waste my time on figuring out could I use MIT or some other license.

Happy hackin’!

Tags: ape, editor, ide, php, pyqt, python.
Categories: Development, Programming.

Backup script for mysql

by Robert Basic on November 05, 2010.
Heads-up! You're reading an old post and the information in it is quite probably outdated.

This post is more of a reminder for myself. Anywayz, a little bash script that backups a database, gzipit and deletes all backups older than 3 days.

#!/bin/bash

DBUSER="user"
DBPASS="pass"
DBDB="dbname"
NOW=$(date +"%Y-%m-%d-%H-%M-%S")
BACKUPROOTDIR="/tmp"
BACKUPSQL="$BACKUPROOTDIR/mysqlbackup-$NOW.sql"
BACKUPGZIP="$BACKUPSQL.gz"

mysqldump -u$DBUSER -p$DBPASS $DBDB > "$BACKUPSQL"
gzip -c $BACKUPSQL > $BACKUPGZIP
rm $BACKUPSQL
find $BACKUPROOTDIR -type f -name "mysqlbackup\*" -mtime +3 | xargs rm

Kudos to @zsteva for looking at it to spot any errors I might have made.

Tags: backup, mysql, script, shell.
Categories: Development.