TypeError: character mapping must return integer, None or unicode

This is pretty unhelpful error message also occurs if you try any method that indirectly use altchars. For example:

base64.urlsafe_b64decode(unicode('aass'))
base64.b64decode(unicode('aass'),'-_')

both fail while the following works:

base64.urlsafe_b64decode('aass')
base64.b64decode(unicode('aass'))

While it’s not complicated to fix it (just convert any unicode string to ascii string), it’s still annoying.

<form>
...
    <input type="hidden" name="to" value="support@example.com" />
...
</form>

as it is likely that if the value of the “to” field changes the message will be sent to the modified address. The problem with this kind of functionality is that it allows a malicious user to send emails from your mail server. More specifically, it can allow spammers to user your benign server t send their spam (and as a side effect you might be flagged as a spammer yourself).

As this case is pretty obvious one doesn’t see many real-life uses of it anymore (but careless programmers used it more often n the past until they learned better). However one can achieve similar goals (spam-wise) by utilizing a common feature in contact forms: the “CC yourself” checkbox.


“CC yourself” is a convention used by some people when mailing, to verify that the email was indeed sent. It had found a place in many contact forms, as people wanted a way to make sure the form indeed works. But contact forms (as well as some mail servers) don’t verify that the email provided as the “from” is indeed owned by whoever fills the form. Combine that with the fact that many contact forms don’t employ CAPTCHAs (to make the form simpler to use), and you’ll get a situation much like the one discussed above.

In the first case there was a usability advantage to the programmer (who could easily re-use the form’s backend for other forms), which can be easily sacrificed for enhanced security. This time it’s worse as this is a usability feature for the user, which many people believe to be very convinient in contact forms.

I think there are several solutions possible:

1. Adding CAPTCHA to the form. This will make life for the spammers harder, but it also hurt the users by raising the bar for filling out the form. Also, nowadays, it getting harder and harder to find a strong yet easy for humans CAPTCHA.
2. Removing the “CC yourself” feature. this hurts the usability of the contact form.
3. Seperating verified users and unverified. Keeping the feature for registered users, but at the same time, removing it or adding CAPTCHA for unverified users. This seems like a good trade-off, but it requires more work and registration is not applicable for all websites.

In my opinion none of the solutions is perfect. It seems that once again spammers hurt the user experience for everybody else in order to fill our inboxes with unsolicited email.

The TiddlyWiki solution seemed great, and I’ve started using it. But as the title says, I merely looked over much simpler, yet as powerful, solution – a simple text file. Porting my rowing log to a simple, old-fashioned, text file provided me all the relevant features of TiddlyWiki, such as search, flexibility and working from usb-stick, while using less space and editable using a basic text-editor (or the powerful vim). Using reStructured Text, I got a nice readable journal that can be later processed into even nicer looking html files.

We all want to believe that we know to match the right tool for a task. But maybe, because we tend to adopt newer technologies and utilities all the time (because for a lot of tasks they do provide better tools), we end up over looking simpler, “old-fashioned”, solutions. If I take a moment now to look around, I can come up with several other places where new stuff is used instead of simpler solutions. Take a look around you, and I’m sure that you will be able to find some too.

So I wrote a patch for the he.po file that fixes the problem.

Index: he.po
===================================================================
--- he.po	(revision 28095)
+++ he.po	(working copy)
@@ -15050,15 +15050,15 @@
 
 #: src/Buffer.cpp:2902
 msgid "\\arabic{enumi}."
-msgstr "\\arabic{enumi}."
+msgstr ".\\arabic{enumi}"
 
 #: src/Buffer.cpp:2908
 msgid "\\roman{enumiii}."
-msgstr "\\roman{enumiii}."
+msgstr ".\\roman{enumiii}"
 
 #: src/Buffer.cpp:2911
 msgid "\\Alph{enumiv}."
-msgstr "\\Alph{enumiv}."
+msgstr ".\\Alph{enumiv}"
 
 #: src/Buffer.cpp:2928 src/insets/InsetCaption.cpp:293
 msgid "Senseless!!! "

While this patch is against the SVN trunk (LyX 2.0), it could also be applied manually to older LyX versions.
After yo apply the patch you should do the following (I assume that you are in the root of the LyX source tree):

cd po/
make he.gmo
cd ../
make install

Now restart LyX and you will see the numbering appear as it should.

The next problem I faced was how to start the Trac automatically upon startup. The solution was to use an init.d script for stating Trac. After some searching, I didn’t find an init.d script for tracd that were satisfactory (mostly poorly written). So I went on an wrote my own init.d script for tracd.

#!/bin/sh
### BEGIN INIT INFO
# Provides:          tracd
# Required-Start:    networking
# Required-Stop:     networking
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start the tracd standalone Trac web server.
### END INIT INFO
# (C) 2008 Guy Rutenberg <http://www.guyrutenberg.com>
 
## Options you should probably change ##
HOSTNAME=127.0.0.1 # to which hostname should we listen
# If you only want to serve one project keep this variable
# empty and set the PROJECT_ENV variable 
ENV_PARENT_DIR=/home/guyru/trac.guyrutenberg.com
PROJECT_ENV=
PORT=9090
# add any additional options (such as authentication) here. If you only have one
# project you should probably add -s here
ADDITIONAL_OPTS=
 
## Options you should probably not change ##
DAEMON=/usr/bin/tracd
NAME=tracd
DESC="web server"
PIDFILE=/var/run/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME
SSD="/sbin/start-stop-daemon"
 
test -x $DAEMON || exit 1
 
set -e
 
. /lib/lsb/init-functions
 
DAEMON_OPTS="--daemonize --pidfile=$PIDFILE --port=$PORT --hostname=$HOSTNAME $ADDITIONAL_OPTS"
if [ -n "$ENV_PARENT_DIR" ]; then
	DAEMON_OPTS="$DAEMON_OPTS --env-parent-dir=$ENV_PARENT_DIR"
else
	DAEMON_OPTS="$DAEMON_OPTS $PROJECT_ENV"
fi
 
case "$1" in
  start)
	log_daemon_msg "Starting $DESC" $NAME
	if ! $SSD --start --quiet\
	--pidfile $PIDFILE --exec $DAEMON -- $DAEMON_OPTS ; then
            log_end_msg 1
	else
            log_end_msg 0
	fi
    ;;
  stop)
	log_daemon_msg "Stopping $DESC" $NAME
	if $SSD --stop --retry 30\
	--pidfile $PIDFILE ; then
	    rm -f $PIDFILE
	    log_end_msg 0
	else
	    log_end_msg 1
	fi
	;;
  restart|force-reload)
	$0 stop
	[ -r  $PIDFILE ] && while pidof -x $NAME |\
		 grep -q `cat $PIDFILE 2>/dev/null` 2>/dev/null ; do sleep 1; done
	$0 start
	;;
  *)
	echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload}" >&2
	exit 1
	;;
esac
 
exit 0

The script begins with a configuration section. You should go over each variable and make sure its value suits you need. The first part is configuration variables you are more likely to change. It includes:

• HOSTNAME – This tells tracd on what hostname to listen. From my experience setting it to anything other than 127.0.0.1 or localhost will cause it to operate on all available hostnames. If you use tracd in conjunction with mod_proxy (this is usually the case if you have Lighttpd) you would want to leave the hostname on 127.0.0.1 so the tracd server won't be accessed directly.
• ENV_PARENT_DIR - If you have multiple projects (all under then same directory) set this to the parent directory. If you only want to serve one project you should leave this empty and set the next variable.
• PROJECT_ENV - Set this to the project environment directory of you project if you serve only one. This variable is ignored if ENV_PARENT_DIR is set to anything but empty.
• PORT - This simply tells tracd on what port to listen.
• ADDITIONAL_OPTS - This variable allows you to pass additional parameters to the tracd. It's the place to add you authentication flags. If you have only a single project and would like to omit the project name in the url (e.g. something like http://trac.example.com) add the -s flag to this variable.

The other part of the configuration allows you to easily adjust the script to your machine. It has variables for specifying the path to the tracd executable and the paths of other things required of the correct operation of the script. In most cases you wouldn't have to change this part.

Now copy the script to /etc/init.d/trac and adjust the configuration to your needs. To enable the script on startup you should use your distro specific tools for managing the rc scripts. On fedora that means you will have to do chkconfig trac on. On Ubuntu you should do update-rc.d trac defaults.

I hope you will find the script useful. If you have any comments or suggestions regarding the script please comment.

UPDATE (13/10/2008):
Here is an version of the script for download.
UPDATE (17/2/2009):
See Starting tracd without Root Privileges at Startup for a different way to start tracd that doesn't require root privileges.

MVC stands for Model View Controller, and represent a way to divide the application to three main parts: Model, View Controller. The Model is responsible for database access and executing queries. The Controller’s task is to handle the business-logic of the application, it should use the Models to access the database along with user-input to construct the information or execute the action the user wishes for. The View is the part visible to the user. Data generated by the Controller part is displayed via the View part, and input that the user enters in the View is passed on to the Controller.

So what pull and push has to do with this? Push and pull describe the relation between the View and the Controller. According to the push model, user actions should be interpreted by the Controller which will generate the data and push it on to the View, hence the “push”. On the other hand, the pull model assumes that the user requires some kind of output (like a list items from the database). The View will access the Controller in order to get the data it needs in order to display the user the kind of output he requested. This is much like the View is “pulling” data from the Controller.

Today, most web-frameworks only use one of the methods above, and do not implement both “push” and “pull”. While in the first look, it may seem good enough as in both ways you can achieve the desired functionality. However, some tasks are better suited by one of them than the other.

For example, when a user wants to make a specific action, like sending a comment, he excepts the action will be carried out, he is less interested in the way the output will tell him that his comment was sent. The user wants to initiate a specific action, which would be mapped to a specific method in on of the controllers. This controller will then “push” the result of the action to a view which shouldn’t care who pushed the data into it. As you can see, this is clearly the place to use a “push” model, because user actions are easily translated to a specific method in the Controller part, which will “push” the output to the View.

The “pull” method has its strengths too. Consider a case where a user asks for a list of customers and what products they bought. The user excepts a specific kind of output. The best way to handle this would be to pass his request to a view that will utilize the different controllers (like the one that handles the customers and the one handling the shopping carts of each customer) in order to create the output the user asked for. The way this request was handled was by the view “pulling” the data from the controllers.

Of course one can implement each one of the examples in both methods, but trying to do so will show you that implementing it in the other method will be more complicated. We can’t ignore the fact that “push” is much better at performing actions and tasks than the “pull” is, and “pull” is superior in handling request to show some kind of data. The framework I’ve built for that site supported both kinds of MVC, allowing us, the developers, to better chose the right way to implement each feature. I would really like to see some more MVC frameworks offering both methods, as I think it can offer great flexibility to the developers. I would really like to read your comments on this matter.

After inspecting the output of ‘dmesg’ I found out that it tries to connect to 192.168.2.255 (192.168.2.* is my network), which is the broadcast address for the network. I tried enabling connection to the address and to my surprise this fixed the problem. I guess samba for some reason requires access for the broadcast for some name/address lookup of hosts in the network.