Here is a quick way to mount a USB thumb drive in Linux. Most distros will recognize the USB stick when you plug it in, but it case they don't then this command comes in handy:
sudo mount -t vfat /dev/sdf1 /mnt/cruzer/
Now you can access and browse the contents of the usb stick by change the current directory to /mnt/cruzer/ . Your mileage may vary and your Linux distro may have a different file system hierarchy.
I recently upgraded to Django version 1.2.1 and I immediatelly noticed that some of my models were broken with the following error:
C:\test>python manage.py syncdb
Traceback (most recent call last):
File "manage.py", line 11, in
execute_manager(settings)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\core\management\__init__.py", line 438, in execute_manager
utility.execute()
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\core\management\__init__.py", line 379, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\core\management\base.py", line 191, in run_from_argv
self.execute(*args, **options.__dict__)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\core\management\base.py", line 217, in execute
self.validate()
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\core\management\base.py", line 245, in validate
num_errors = get_validation_errors(s, app)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\core\management\validation.py", line 28, in get_validation_errors
for (app_name, error) in get_app_errors().items():
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\db\models\loading.py", line 146, in get_app_errors
self._populate()
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\db\models\loading.py", line 61, in _populate
self.load_app(app_name, True)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\db\models\loading.py", line 78, in load_app
models = import_module('.models', app_name)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\utils\importlib.py", line 35, in import_module
__import__(name)
File "..\tso\blog\models.py", line 50, in
class Category(models.Model):
File "..\tso\blog\models.py", line 53, in Category
slug = models.SlugField(unique=True, prepopulate_from=('title',), help_text='Used in the category URL. Must be unique')
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\db\models\fields\__init__.py", line 988, in __init__
super(SlugField, self).__init__(*args, **kwargs)
File "C:\Python26\lib\site-packages\django-1.2.1-py2.6.egg\django\db\models\fields\__init__.py", line 542, in __init__
super(CharField, self).__init__(*args, **kwargs)
TypeError: __init__() got an unexpected keyword argument 'prepopulate_from'
So I did a little bit of research on this problem and I found the following explanation for what is going on:
Changed prepopulate_from to be defined in the Admin class, not database field classes
As of [4446], the prepopulate_from option to database fields no longer exists. It's been discontinued in favor of the new prepopulated_fields option on class Admin. The new prepopulated_fields option, if given, should be a dictionary mapping field names to lists/tuples of field names. This change was made in an effort to remove admin-specific options from the model itself. Here's an example comparing old syntax and new syntax:
# OLD: class MyModel(models.Model): first_name = models.CharField(max_length=30) last_name = models.CharField(max_length=30) slug = models.CharField(max_length=60, prepopulate_from=('first_name', 'last_name')) class Admin: pass # NEW: class MyModel(models.Model): first_name = models.CharField(max_length=30) last_name = models.CharField(max_length=30) slug = models.CharField(max_length=60) from django.contrib import admin class MyModelAdmin(admin.ModelAdmin): prepopulated_fields = {'slug': ('first_name', 'last_name')} admin.site.register(MyModel, MyModelAdmin)
The above is taken from the Django wiki page that talks about the newforms-admin branch.
A while back I wrote about the address line of the browser being the new command line. It turns out I was wrong. The command line itself is the new command line.
I ran into this Google Code project today via my tweeter feed. GoogleCL allows the nerd in me to interact directly with several Google services from a shell prompt. It includes interfaces to Blogger, Picasa, Calendar, Contacts, Docs, and YouTube. You can find several scripting examples under the project's Wiki.
The fact that this is a python script and it's open source is really interesting to me. I am thinking that I need to integrate all of this into an Emacs mode.
I just posted this question to StackOverflow and I am repeating it here for posterity as the pastebin code expires after a month:
More than a question, per se, this is an attempt to compare notes with other people. I wrote a generic History class that emulates the functionality of a browser's history. I am trying to wrap my head around how far to go when writing unit tests for it. I am using NUnit. Please share your testing approaches below.
The full code for the History class is at pastebin.com: http://pastebin.com/ZGKK2V84. A full version of the code is also available below:
using System;
using System.Collections.Generic;
namespace Gorauskas.DataStructures {
///
/// A history data structure that provides the same functionality
/// as a browser history, but allows you to use any type
///
/// The type parameter
public class History<T> {
private Stack<T> _forward = new Stack<T>();
private Stack<T> _backward = new Stack<T>();
private T _current;
public History() { }
///
/// This contructor set the Current pointer to an initial object of type T
///
/// An item of type T
public History(T item) {
this._current = item;
}
///
/// Returns the current item that it is pointing to
/// Pushes the state of the current pointer into the backward stack
/// and sets the new current item. If the forward stack has items in it
/// then clear that too.
///
public T Current {
get {
return this._current;
}
set {
if(this.CanMoveForward)
this._forward.Clear();
if (!(this._current == null))
this._backward.Push(this._current);
this._current = value;
}
}
///
/// Tells if the current pointer can be moved forward in history.
///
public bool CanMoveForward {
get { return this._forward.Count > 0; }
}
///
/// Tells if the current pointer can be moved backward in history.
///
public bool CanMoveBackward {
get { return this._backward.Count > 0; }
}
///
/// Moves the current pointer one item back in history
///
/// The current item
public T Back() {
if (this.CanMoveBackward) {
this._forward.Push(this._current);
this._current = this._backward.Pop();
}
return this._current;
}
///
/// Moves the current pointer one item forward in history
///
/// The current item
public T Forward() {
if (this.CanMoveForward) {
this._backward.Push(this._current);
this._current = this._forward.Pop();
}
return this._current;
}
///
/// Adds the entire history in chronological order to a list of T
///
/// A ordered list of history items
public List<T> Dump() {
List<T> l = new List<T>();
if (this.CanMoveForward)
l.AddRange(this._forward.ToList<T>().Reverse<T>());
if (!(this.Current == null))
l.Add(this._current);
if (this.CanMoveBackward)
l.AddRange(this._backward.ToList<T>());
return l;
}
}
}
A little while back I wrote up my notes on how to build and install Emacs from souce on Ubuntu.
I have now automated the task in the form of the crude script provided below. The script takes one parameter: gui. This parameter tells the build whether you intend to do a GUI or command line only build of Emacs. It also writes out some messages to a file called emacs-build.log ... Enjoy!
#! /bin/bash
echo "Building @`date`" | tee -a ~/emacs-build.log
mkdir ~/emacs-src
cd ~/emacs-src
echo "Installing pre-requisites" | tee -a ~/emacs-build.log
apt-get -q -y install build-essential gcc git-core texinfo libncurses5-dev
if [ "$1" = gui ]; then
echo "Installing GUI pre-requisites" | tee -a ~/emacs-build.log
apt-get -q -y install libgtk2.0-dev libtiff4-dev libgif-dev libjpeg62-dev libpng12-dev libxpm-dev
fi
echo "Cloning Emacs Git Repo" | tee -a ~/emacs-build.log
git clone git://git.savannah.gnu.org/emacs.git
cd ./emacs
echo "Configuring build" | tee -a ~/emacs-build.log
if [ "$1" = gui ]; then
./configure
else
./configure --without-x
fi
echo "Building source code" | tee -a ~/emacs-build.log
make
echo "Installing emacs" | tee -a ~/emacs-build.log
make install
echo "Clean up" | tee -a ~/emacs-build.log
cd ~/
rm -rf ~/emacs-src
echo "All Done!" | tee -a ~/emacs-build.log
pyc.py will be available at C:\Program Files (x86)\IronPython 2.6\Tools\Scripts or wherever you installed IronPython on your system. If you have earlier versions of IronPython then pyc.py will be available as a separate download in the samples package.pyc.py you can create console or Windows assemblies from your python scripts. Basic usage looks like this:
ipy pyc.py /out:myprogram.exe /main:mainfile.py /target:exe
program.py support.py
myprogram.exe (/out) which is a console application (/target) and will execute the code in mainfile.py first (/main) and will also include code from program.py and support.py in the assembly.
Interesting comment from the trenches:
After much testing, it's clear that Postel's advice to protocol designers ("be liberal in what you accept, and conservative in what you send") invites a natural-law repercussion for JS as "protocol":
"If you are liberal in what you accept, others will utterly fail to be conservative in what they send."
Found here: http://mxr.mozilla.org/mozilla-central/source/js/src/jsscan.cpp#1464 while looking at SpiderMonkey source code.
I have a Xubuntu 9.04 machine that is hosting some VMs running on VMWare Server. I recently upgraded a bunch of packages on the host machine and then I noticed that the VMWare Server was not starting automatically anymore. I tried running it manually and I got the error message: vmware is installed, but it has not been (correctly) configured for this system.
What happened is that one of the upgraded packages was the Linux Kernel
and a new Kernel version will break VMWare because it originally compiled for
the previous Kernel version that was on the machine. To fix
this I had to run the /usr/bin/vmware-config.pl script to reconfigure
and recompile several components. After running the script, VMWare
server started up again as normal.
Let me know if you had this problem before.
Every so often I have to setup a web development server and one of the first things I have to have on that server is Emacs. As an Emacs fanatic, I need to have the very latest bleeding-edge version. In order to ensure that, I clone the official git repository into my home directory and then I compile and build from there. Most of the time I will be performing the steps below on a Ubuntu Server distribution (these work on versions 8.10, 9.04, and 9.10) without X installed.
sudo apt-get install build-essentials gcc git-core texinfo \
libncurses5-dev
git clone git://git.savannah.gnu.org/emacs.git
cd ./emacs
sudo ./configure --without-x
sudo make
sudo make install
Some notes: The need for the build-essentials, gcc, and git-core are pretty obvious; the texinfo package is needed for the makeinfo dependency; and the libncurses5-dev is needed for the termcap.h dependency.
The above will also work on a desktop distro, but you will be limited to a terminal version of Emacs. In order to install a graphical version of Emacs you will also need to install the following extra packages:
sudo apt-get install libgtk2.0-dev libtiff4-dev libgif-dev \
libjpeg62-dev libpng12-dev libxpm-dev
The above line will also install a bunch of other dependencies needed by the libraries. Don't forget to also remove the --without-x parameter and run just this line:
sudo ./configure
Let me know how it works for you.
I was playing with .NET serialization at work the other day and got curious about how Python does it. Serialization is a little confusing in the .NET world, but it's not an insurmountable task to grasp it. For one, there is more than a single implementation of serialization within the .NET base class library, or namely, System.Xml.Serialization and System.Runtime.Serialization, which respectively implement XML and binary serialization. The techniques used in each implementation are also disparate, having the binary serialization make heavy use of class attributes, while the XML implementation uses a method call to XmlSerializer.Serialize.
The Python implementation of serialization is much simpler, concise and easier to understand. It is implemented as a Standard Library module called Pickle. The actions to serialize and deserialize classes are implemented as simple function class and there is no need to put attributes on classes. Let's see how it works. First import the pickle module and then declare a class called Person as in the code below:
import pickle
class Person(object):
def __init__(self, first_name=None, last_name=None, age=None):
self.first_name = first_name
self.last_name = last_name
self.age = age
Now create two instances of the Person class above and place them in a list.
p1 = Person('Jane', 'Doe', 26)
p2 = Person('John', 'Hancock', 33)
people = []
people.append(p1)
people.append(p2)
Next serialize the list to a file and then read it back into a new list. First serialize the list:
fname = 'peoplelist.dat'
f1 = open(fname, 'wb')
pickle.dump(people, f1)
f1.close()
Finally, read the contents of the serialized file back into a new list and print out the name and age of each person:
f2 = open(fname)
new_people = pickle.load(f2)
for person in new_people:
print '%s %s is %d years old.' % (person.first_name, person.last_name, person.age)
That's it... Serialization in Python is just too easy!
