First post of 2010

Just because I haven't done it in awhile.

Give me a function that given a line, describes the next

1
11
21
1211
111221
312211
13112221
1113213211


char* get_next_line(char* line)
{
char next_line[4096];
int next_line_ndx = 0;

char letter = line[0];
int num_letters = 0;

for (int i = 0; i < strlen(line); ++i)
{
if (letter != line[i+1])
{
next_line[next_line_ndx] = num_letters + '0';
next_line_ndx++;
next_line[next_line_ndx] = letter;
next_line_ndx++;
next_line[next_line_ndx] = 0;

letter = line[i+1];
num_letters = 0;
}
else
{
num_letters++;
}
}

return next_line;
}

breadth first search of binary tree (w/o the formatting)

7
/ \
1 2
/ \ /
0 3 4
\
2

7
1 2
0 3 4
2



def traverse_tree(node):
q = []
last_level = 0
current_level = 0
q.append([node, current_level])

while len(q) > 0:
node, current_level = q.pop()

if current_level != last_level:
last_level = current_level
print "\n"
print node + " "

left_child = node.left
right_child = node.right

if left_child not NULL:
q.append([left_child, current_level + 1])

if right_child not NULL:
q.append([right_child, current_level + 1])

MySQL restart on Mac OS X

This is the simplest way to restart the server on Mac OSX that I found

my-computer:~ me$ mysqladmin -uroot -p shutdown
Enter password:
my-computer:~ me$ sudo mysqld_safe
Starting mysqld daemon with databases from /sw/var/mysql

Voted

I voted so I have the right to complain.

MySQL Python API

If you try to install the python API for MySQL on Leopard, and receive the following message:

lipo: can't open input file: /var/tmp//ccDsRjet.out (No such file or directory)

make sure you check out this.

Nice Macports explanation for Ruby Rails

http://paulsturgess.co.uk/articles/show/46-using-macportsdarwinports-to-install-ruby-on-rails-mysql-subversion-capistrano-and-mongrel-on-mac-os-x

Installing BerkeleyDB perl module from CPAN

I was getting an error executing:

cpan -i BerkeleyDB

This seemed to be because I did not have Berkeley installed on my mac.  Well no problem, just execute

port install db46

from Macports.  After that finishes, just set up a link in /usr/local e.g.

ln -s  /usr/local/BerkeleyDB.4.6/ /usr/local/BerkeleyDB

and then 

cpan -i BerkeleyDB

should work.

Install perl module off cpan

it's easy

cpan -i [module]

Enable sending email on Mac OS X

It wasn't completely obvious to me, but here is what you need to execute in order to be able to send email from your Mac.

in a terminal:

postfix start

Installing and setting up a fink installed MySQL with a non-default data directory

So I assume you have successfully executed: sudo fink install mysql

Create or edit /etc/my.cnf and add or change the keyword datadir to the directory you want e.g.

[mysqld]

datadir=/Volumes/another/directory

[mysqld_safe]

datadir=/Volumes/another/directory

During installation, Fink set up some files and directories in /sw/var/mysql.  Copy the contents of this directory to your new directory e.g.

sudo cp -r /sw/var/mysql/* /Volumes/another/directory

Go to /Volumes/another/directory and set the owner of all contents to mysql e.g.

sudo chown -R mysql /Volumes/another/directory.

At this point you should be able to run 'sudo mysqld_safe.'

fink Mysql on Macbook OSX 10.5 leopard

I installed mysql from fink and received some unwelcome news.

My-MacBook:~ me$ sudo mysqld_safe
Password:
chown: mysql: Invalid argument
Starting mysqld daemon with databases from /sw/var/mysql
STOPPING server from pid file /sw/var/mysql/My-MacBook.local.pid
080517 14:39:45 mysqld ended

After looking at /sw/var/mysql/My-MacBook.local.err, it seemed I was missing the user mysql. So I snooped around google and found the answer. Based on this, I executed the following commands:

sudo dscl localhost -create /Local/Default/Users/mysql

sudo dscl localhost -create /Local/Default/Users/mysql NFSHomeDirectory /var/empty
sudo dscl localhost -create /Local/Default/Users/mysql Password '*'
sudo dscl localhost -create /Local/Default/Users/mysql PrimaryGroupID 74
sudo dscl localhost -create /Local/Default/Users/mysql RealName "MySQL Server"
sudo dscl localhost -create /Local/Default/Users/mysql UniqueID: 74
sudo dscl localhost -create /Local/Default/Users/mysql UserShell: /usr/bin/false

My next attempt to start mysqld_safe gave me some more bad news:

My-MacBook:var me$ sudo mysqld_safe Password:
chown: mysql: Invalid argument
Starting mysqld daemon with databases from /sw/var/mysql
STOPPING server from pid file /sw/var/mysql/My-MacBook.local.pid
080517 17:11:24 mysqld ended

This one was easy though. Just go to /sw/var and execute chown -R mysql mysql. You should be good to go from here. sudo mysqld_safe& should work just fine.

Adobe Flex license key Leopard OSX

If you ever receive a message like "License key is invalid" when you enter in your valid license
for Adobe Flex on OSX, try switching to an admin account. For some reason when you enter the license key into Flex Builder (or the Eclipse plug-in) under a non-admin account, you cannot 'activate' the installation.

gem install mysql mac osx leopard

gem install mysql -- --with-mysql-config=`which mysql_config`

Also you may need some additional hacking to get it all working.

Updating locate on Mac OSX

Update locatedb on your Mac OSX with:
sudo /usr/libexec/locate.updatedb

Debugging ruby rails in production

Helpful little thing that helped me debug my ruby rails production system.

shell$ [RAILS_ROOT]/script/console production

So here you can invoke a model (e.g. User.new), call helper methods (UserHelper.authenticate(user, pass)), etc.

Ruby Rails column type to MySQL datatype

lifted from PackT.

Migration column type...	Converts to MySQL field type...	Available options1
:binary	TINYBLOB, BLOB, MEDIUMBLOB, or LONGBLOB2	:limit => 1 to 4294967296 (default = 65536)2
:boolean	TINYINT(1)	-
:date	DATE	-
:datetime	DATETIME	-
:decimal	DECIMAL	:precision => 1 to 63 (default = 10) :scale => 0 to 30 (default = 0)3
:float	FLOAT	-
:integer	INT	:limit => 1 to 11 (default = 11)
:primary_key	INT(11) AUTO_INCREMENT PRIMARY KEY	-
:string	VARCHAR	:limit => 1 to 255 (default = 255)
:text	TINYTEXT, TEXT, MEDIUMTEXT, or LONGTEXT2	:limit => 1 to 4294967296 (default = 65536)2
:time	TIME	-
:timestamp	DATETIME	-

Production Rails Database

To make a production version of a database defined in rails.

rake db:migrate RAILS_ENV="production"

phpMyAdmin plug

Man... gotta use phpMyAdmin for looking at your MySQL database. On Mac use 'Fink Commander' and look for phpMyAdmin. Follow the configuration instructions here. In order for me to get it working, I had to set the following properties:

$cfg['Servers'][$i]['socket'] = '/tmp/mysql.sock';
$cfg['Servers'][$i]['connect_type'] = 'socket';

Instance variable in viewer for ActionMailer

Using the ActionMailer in your Ruby on Rails application, I wanted to display a variable in the viewer. If the content_type is "text/html", the body needs to have the instance variable symbol e.g. body :var => var. In the viewer, you may reference this variable with <%= @var %>.