Summery Gossamer

How to install ruby on rails in the right way

2012-02-08T10:04:00.000-08:00

step 1:
install rvm
Don't forget to source ~/.bashrc or restart shell
step 2:
$ rvm requirements
Then install requirements needed for your ruby
step 3:
$ rvm install 1.9.2 # installs required ruby version
$ rvm 1.9.2
$ gem install rails -v 3.2

How to deploy with Mercurial aka HG on rails3.1

2011-12-25T20:33:00.001-08:00

1. Install Phusion Passenger module (www.modrails.com/) on top of Apache2 or Nginx
2. Edit .hg/hgrc on the destination (production server).

[hooks] incoming = hg update -C && RAILS_ENV=production rake db:migrate && bundle exec rake assets:precompile && touch tmp/restart.txt
(http://pastie.org/3073448)

Let's explain briefly rails aspects of [hooks].

RAILS_ENV=production rake db:migrate -- sets environment to production mode and migrates the database.

bundle exec rake assets:precompile -- precompiles scss (sass), coffescript (js) and image files from app/assets to the public/assets directory.

touch tmp/restart.txt -- sends Passenger command to restart the server.

Enjoy!

How to solve: This Terminal Emulator is not functional because no 'bash' shell could be found in Aptana Studio 3

2011-09-04T03:19:00.000-07:00

This Terminal Emulator is not functional because no 'bash' shell could be found.
Please correct the problem and restart the IDE.

Info

Let's see the Aptana's Studio 3 log file.

java.io.IOException: Cannot run program "/opt/Aptana Studio 3/plugins/com.aptana.terminal_3.0.0.1310755723/os/linux/x86/redtty"

Solution

chmod +x "/opt/Aptana Studio 3/plugins/com.aptana.terminal_3.0.0.1310755723/os/linux/x86/redtty"

Then File -> Restart

How to search for a particular word in SQLite database

2011-07-19T07:28:00.001-07:00

I have written simple python script that looks through SQLite database
for any entry occurrence in any table in any column.
Here it is

If you have any questions, please leave your comment.

How to build html-tables on the fly

2011-07-17T06:35:00.000-07:00

Now we're going to discuss how to build html tables from JSON response.

First we need library that can easily handle JSON. For instance, JQuery.
Suppose, we have included core JQuery library.

Here is the htmltable.js
Now all that we need is just to include that htmltable.js file and load any JSON like that:


function dynamicTable(URL, id){
    url = URL + '?id=' + id
    
    $.getJSON(url, function(data) {
        captions = {'code':'Code','descr':{'content':'Description','attr': 'style="width: 800px"'}}
        html_table = build_table(data, captions);
        $('#anyDivId').html(html_table);
    });
}

Ancient Mysteries - Nazca Lines

2011-07-12T13:09:00.001-07:00

How to install pysqlite (python sqlite binding interface) on Ubuntu Linux

2011-07-06T11:26:00.001-07:00

First you need development libraries:

$ sudo apt-get install libsqlite3-dev

Then you have to download pysqlite files from http://code.google.com/p/pysqlite/
Next steps are usual: unpack and change dir

After that run (you should have gcc - GNU C compiler - of course):

$ python setup.py build

After compilation runs successfully you are able to install pysqlite with:

$ sudo python setup.py install

That's all

How to resize many images by extension at once (Linux, Unix)

2011-07-05T04:40:00.001-07:00

First you need to install ImageMagick.

Then just change dir and type:

$ mogrify -resize 2048x1536 *.jpg

Where 2048x1536 is new size of all images with .jpg extension.

How to install MySQLdb on Ubuntu Linux

2011-07-04T14:19:00.001-07:00

Many python frameworks like web.py require MySQLdb.

Here is how I installed it.

Firstly,
sudo apt-get install libmysqlclient-dev python2.6-dev
then
sudo easy_install MySQL-python

or download from http://sourceforge.net/projects/mysql-python/

extract archive and change dir then

python setup.py build
sudo python setup.py install

Simple optical illusion

2011-07-03T13:02:00.001-07:00

On this image all lines *are* parallel. Enjoy!

Simple php cache v2

2011-06-18T08:27:00.000-07:00

Here is more convenient version.

Use it like this


<?php
$cached_obj = new SimpleCache('file_to_save_in');

if (!$obj=$cached_obj->retrieve()) {
    $obj = long_calculation(); //or any other function
    $cached_obj->save($obj);
}
echo $obj;
?>

SimpleCache class listed below


<?php

class SimpleCache
{
    //@author allez

/*
        //how to use it
        $cached_obj = new SimpleCache('cache_identifier');

        if (!$obj=$cached_obj->retrieve()) {
            $obj = main(); //or any other function
            $cached_obj->save($obj);
        }
        return $obj;
 */

    //max cache life time in seconds
    const max_time = 1800;
    //folder to save your cache
    const temp_folder = '/tmp';

    // File name of cached contents
    private $fname;

    public function __construct($name)
    {
        $this->name = $name;
        $this->fname = $name . '.cache';
    }

    public function outdated()
    {
        if (!file_exists($this->fname)) return true;
        $simpleCache_time = filemtime($this->fname);
        if (SimpleCache::max_time + $simpleCache_time < time()) return true;
        return false;
    }

    public function retrieve()
    {
        if ($this->outdated()) return false;
        $simpleCache_contents = file_get_contents($this->fname);
        return unserialize($simpleCache_contents);
    }

    public function save($cached_list)
    {
        $cf = fopen(SimpleCache::temp_folder .'/'. $this->fname, 'w') OR die('Can not save '. $this->fname);
        fputs($cf, serialize($cached_list));
        fclose($cf);
    }

    public function clean()
    {
        if(file_exists($this->fname)) unlink($this->fname);
    }
}

Simple php cache implementation

2011-06-18T08:09:00.000-07:00

Sometimes you just need cache to save your valuable processor time. Here is simplified basement for your application.


class SimpleCache
{
    //@author allez

/*
        //how to use it
        $cached_obj = new SimpleCache('storage_name');

        if ($cached_obj->outdated()) {
            $obj = main(); //or any other function
            //$cached_obj->clean(); //purge cache if necessary
            $cached_obj->save($obj);
            echo $obj;
        } else {
            echo $cached_obj->retrieve();
        }
 */

    //max cache life time in seconds
    const max_time = 1800;
    //folder to save your cache
    const temp_folder = '/tmp';

    // File name of cached contents
    private $fname;

    public function __construct($name)
    {
        $this->name = $name;
        $this->fname = $name . '.cache';
    }

    public function outdated()
    {
        if (!file_exists($this->fname)) return true;
        $simpleCache_time = filemtime($this->fname);
        if (SimpleCache::max_time + $simpleCache_time < time()) return true;
        return false;
    }

    public function retrieve()
    {
        if ($this->outdated()) throw new Exception('Cache is outdated');
        $simpleCache_contents = file_get_contents($this->fname);
        return unserialize($simpleCache_contents);
    }

    public function save($cached_list)
    {
        $cf = fopen(SimpleCache::temp_folder .'/'. $this->fname, 'w') OR die('Can not save '. $this->fname);
        fputs($cf, serialize($cached_list));
        fclose($cf);
    }

    public function clean()
    {
        if(file_exists($this->fname)) unlink($this->fname);
    }
}

Change encoding from windows-1251 (cp-1251) to Unicode (UTF-8) quickly

2011-06-02T07:22:00.001-07:00

Sometimes it is easier to write your own script than to find what you need in the Internet. I guess that something like file_save_contents already exists but do I need to waste my time now?

THE SCRIPT IS:

#!/usr/bin/env php
<?php
//@author allez
define('INFO', "\n\n". $_SERVER['argv'][0] ." file/dir1 [file/dir1 ...]
Changes encoding from cp1251 to utf8 in all listed files and directories.
Use * to list all the files in directory\n\n");
function file_save_contents($con, $location)
{
 $f = fopen($location, 'w') OR die("can not modify $location\n");
 fputs($f, $con);
 fclose($f);
}
function process($fname)
{
 print "Changing $fname\n";
    $a = file_get_contents($fname);
    $a = iconv('cp1251', 'utf8', $a);
 file_save_contents($a, $fname);
}
function process_dir($dn)
{
 $dr = opendir($dn);
 while($a = readdir($dr))
 {
     if ($a[0] != '.') {
         $tname = "$dn/$a";
         if(is_dir($tname)) process_dir($tname);
         else process($tname);
     }
 }
 closedir($dr);
}
function main()
{
 if (count($_SERVER['argv']) == 1) print INFO;
 else foreach($_SERVER['argv'] as $key => $val)
 {
     if($key > 0) {
         try {
             if (is_dir($val)) {
                 process_dir($val);
             }
             else {
                 process($val);
             }
         } catch (Exception $e) {
             print $e();
         }
     }
 }
}
main();

//P.S. Do not forget to chmod +x <scriptname>

Requiem for a Dream

2011-04-24T21:35:00.000-07:00

How about remake of 'Requiem for a Dream' movie? But instead of TV and/or drugs there should be social media present.

Google science

2011-03-15T06:12:00.001-07:00

Python vs. Ruby (Dice throwing again)

2011-02-15T09:57:00.000-08:00

Referring to the August post, I must say that Python is as object oriented as Ruby is. It has similar syntax.

Python


#!/usr/bin/env python

from random import random

def b():
  a = int(random() * 6)
  print a

for i in range(15) : b()

Ruby


#!/usr/bin/env ruby

def b
a = rand(6) + 1
puts a
end

15.times do
b
end

As we know...

2010-11-14T13:42:00.001-08:00

As we know,
There are known knowns.
There are things we know we know.
We also know
There are known unknowns.
That is to say
We know there are some things
We do not know.
But there are also unknown unknowns,
The ones we don't know
We don't know.

Model

2010-11-10T08:29:00.001-08:00

In the most general sense, a model is anything used in any way to represent anything else.
(from encyclopaedia)

Weird a bit

2010-09-04T04:55:00.001-07:00

The Highest Peak in Ukraine: Photos

2010-08-26T09:41:00.001-07:00

Hoverla (2061 m) is the highest mountain in Ukraine. Here I have spent Ukrainian Independence Day (August 24, 2010).

Open books - free ebooks about computers and programming

2010-08-15T09:34:00.000-07:00

O'Reilly open books

Galileo open books

Ruby vs. PHP (throwing dice sample)

2010-08-02T04:39:00.000-07:00

I am not yet a guru, but it is not hard to see the profit

Ruby


#!/usr/bin/env ruby

def b
  a = rand(6) + 1
  puts a
end

15.times do
  b
end

PHP


#!/usr/bin/env php

<?php
  
function b()
{
  $a = rand(1, 6);
  echo "$a\n";
}

for ($i = 0; $i < 15; ++$i) {
  b();
}

Both codes above print out throwing 15 dice.

Tip: What to do if your phone is stolen?

2010-07-31T06:02:00.000-07:00

Sometimes you might find your phone is not in the right place. Maybe it is lost?
What to do with files that might have trapped not in the right hands.

But don't panic! Here is simple solution.

You can download it here or visit home page of the official site.

A bit of horror

2010-07-29T01:01:00.000-07:00

Frankenstein-like film. But more horror.
In short, don't watch that!

Obsessive ideas

2010-07-28T12:59:00.000-07:00

I like watching display of electronic watch when seconds change minutes, minutes change hours.

There are many kinds of obsessive ideas. I.e., when you go somewhere trying counting and/or trapping right squares of tiles under your feet;
when nothing is threatening your life and you try to change your movement according to bypassing cars and so on...

Almost everyone had at least one obsessive idea in his/her live. Such kind of psycho activity was described in details by many of psychologists, particularly by Leonhard.