Mind Reference

Thoughts on SQL vs ORM

2013-02-06T15:30:00.000+03:00

The question of persistence implementation arise often. I found repository pattern very valuable due to separation of concerns, mediate between domain model and data source (mock, file, database, web service, etc). The database data source is somewhat specific since you can proceed with SQL functions or ORM. Here are some thoughts why you might prefer SQL functions over ORM in your next project:

wheezy web: Quick Start i18n Project

2013-01-16T18:00:00.000+03:00

wheezy.web is a lightweight, high performance, high concurrency WSGI web framework with the key features to build modern, efficient web. Here we will use an i18n (multilingual internationalization) project quick start to build a new project. Download quickstart-i18n.zip and extract. Rename extracted directory `quickstart-i18n` to meet your project name, e.g. mysite and open terminal in that

wheezy web: Quick Start Empty Project

2013-01-15T21:00:00.000+03:00

wheezy.web is a lightweight, high performance, high concurrency WSGI web framework with the key features to build modern, efficient web. Here we will use an empty project quick start to build a new project. Download quickstart-empty.zip and extract. Rename extracted directory `quickstart-empty` to meet your project name, e.g. mysite and open terminal in that directory. The empty project

How to create Jail in FreeBSD

2012-12-11T22:30:00.000+03:00

Operating system virtualization is the most effective way to utilize your system resources, jails let you setup isolated mini-systems. Jails are explains well in handbook however, from practical standpoint of view, the presented material is incomplete. Here we will setup few scrips that follow handbook's 'Application of Jails' article and enhance with few missing features. Let note preliminary

How to Send Mail in Python

2012-12-03T23:30:00.000+03:00

There are several use cases how you can send an email message using Python: Plain Mail: an email message with plain text or html content. Mail with Attachment: an email message with attached document. Alternative Mail Views: you provide a convenient way to email recipients to view your message in plain text or html with optional rich content including images, etc. Here is an example of

How to ship eggs with pyo files only in Python

2012-11-28T21:00:00.000+03:00

There is sometimes a need to ship python egg distribution with pyo files only. There is confusion using bdist_egg command since it doesn't have any options to do that; instead, you can instruct install_lib command. Here is what you need in setup.cfg file: [install_lib] compile = 0 optimize = 2 [bdist_egg] exclude-source-files = 1 Issue the following command to build egg. python setup.py -q

Python Web Frameworks Excessive Complexity

2012-11-20T20:30:00.000+03:00

Cyclomatic (or conditional) complexity is a metric used to indicate the complexity of a source code. In this post we will take a look at web frameworks source code and estimate excessive complexity, something that is beyond recommended level of 10 (threshold that points to the fact the source code is too complex and refactoring is suggested). Here is a list of web frameworks examined: bottle

Lazy Attribute in Python

2012-11-15T22:00:00.000+03:00

A lazy attribute is an attribute that is calculated on demand and only once. Here we will see how you can use lazy attribute in your Python class. Setup environment before you proceed: $ virtualenv env $ env/bin/pip install wheezy.core Let assume we need an attribute that is display name of some person Place the following code snippet into some file and run it: from wheezy.core.descriptors

Duck Typing Assert in Python

2012-11-08T20:00:00.000+03:00

People who come from strongly typed languages that offer interfaces often are confused by lack of one in Python. Python, being dynamic typing programming language, follows duck typing principal. Here we will see how programmer can assert duck typing between two Python classes. Setup environment before proceed: $ virtualenv env $ env/bin/pip install wheezy.core Let play a bit with duck test `

How to generate account number?

2012-11-03T00:00:00.000+03:00

Requirements for `account number` generator: Issue pseudo random consistent number (must be unique for dozen millions of records) Easy check validity (without a need to make a database call) We will use Feistel cipher to generate pseudo random number (positive only) from a sequential numbers (e.g. returned by nextval() for a posgresql sequence). This algorithm is taken as basis for the `

wheezy web: introduction

2012-10-26T14:00:00.000+03:00

The key of success for any medium to high complexity system is in separation of domain concerns. Given that choice in architectural design for web framework, the development activities are split by distinct, non-dependent parts. The wheezy.web is a lightweight WSGI web framework and serves a glue purpose between various other packages developed under wheezy.* umbrella in loosely coupled way, it

Python Web Caching Benchmark

2012-10-25T16:30:00.000+03:00

Content caching is the most effective type of cache. This way your web handler is not executed to determine a valid response to user, instead one returned from cache. Since the operation is that simple, it should be the maximum possible speed your `real world` application capable to provide. There are several use cases when content caching is applicable: Site: the site content is changed rarely

Python Templates Benchmark

2012-10-23T15:30:00.000+03:00

Python template engines offer high reusability of markup code and the following features are used by content developers most of the time: Includes: useful to incorporate some snippets of content that in most cases are common to the site, e.g. footer, scripts, styles, etc. Extends: useful to define a master layout for the majority of the site content with placeholders, e.g. sidebar,

Python Web Frameworks PEP8 Consistency

2012-10-18T15:00:00.000+03:00

The code is read much more often than it is written. The PEP8 guidelines are intended to improve the readability of code. Readability counts, no doubt, but readability consistency is important, it is equally important to know when to be inconsistent. The report below makes excuse for the following: E501 line too long (> 79 characters) E231 missing whitespace after ',:' W291 trailing whitespace

Python Web Reverse URLs Benchmark

2012-10-15T17:00:00.000+03:00

How fast python web frameworks reverse urls? While routing is a mapping of incoming request to a handler, url reverse function is designed to build urls for those handlers. A web page may have a number of urls from few dozen to hundreds... all related to your web site (e.g. links between related pages, tag cloud, most viewed posts, etc). A typical web application usually has deal with the

Python Web Routing Benchmark

2012-10-09T16:30:00.000+03:00

How fast python web framework process routing (some calls this URL dispatch)? A typical web application usually has the following routes: Static: the URL path is fixed and never changes, e.g. https://bitbucket.org/explore. Dynamic: the URL path is constructed dynamically and can include semantic information, e.g. https://bitbucket.org/jsmith/dotfiles/downloads, in this case jsmith is user,

apt-get: update only required translations

2012-10-04T20:30:00.000+03:00

apt Acquire::Languages can be set to declare which translations you want downloading. The variable "environment" specifies that apt should check $LC_MESSAGES. Here we go: # eliminate any lists you might have rm -rf /var/lib/apt/lists/ # set languages you need echo 'Acquire::Languages { "environment"; "en"; };' > \ /etc/apt/apt.conf.d/99lang # update lists apt-get update If you need just

Python Fastest Web Framework

2012-09-18T15:00:00.000+03:00

What is the fastest web framework for Python? In this post we will examine a trivial 'Hello World!'. See also: Performance Benchmarks Routing Reverse URLs Caching Code Quality PEP8 Consistency Excessive Complexity Template Engines Big Table Includes, extends and widgets The application (see source) is written for various Python web frameworks and deployed to uWSGI application container (

How to restore vim screen when exiting

2012-08-22T20:00:00.000+03:00

When you exit vim it does not restore the terminal screen (particularly in FreeBSD), here is how to fix that (file ~/.vimrc): " Restore terminal screen when exiting Vim if &term =~ "xterm" let &t_ti = "\<Esc>[?47h" let &t_te = "\<Esc>[?47l" endif

Rebuilding World and Kernel on FreeBSD

2012-08-19T21:00:00.000+03:00

Building the world and kernel on FreeBSD is just few steps procedure. The Handbook explains everything in great details. Here is short version. Synchronize the OS source code (see here). Configure make.conf. Optional. Configure world options (file /etc/src.conf): WITHOUT_AMD= WITHOUT_ASSERT_DEBUG= # Need only few utilities from bind WITHOUT_BIND_DNSSEC= WITHOUT_BIND_ETC=

Keep FreeBSD up to date with csup

2012-08-19T20:30:00.000+03:00

csup is a simple tool to keep you FreeBSD source and/or ports collection up to date (rewrite of CSVup in C). There are a number of mirrors around the world hosting the source code and you need to select one that is closest to your location. Use a tool like traceroute to find a one that responds best (shortest path, low delays). Ports It is recommended to copy ports configuration file (known as

FreeBSD Binary/Security Updates

2012-08-19T20:00:00.000+03:00

freebsd-update is a tool to fetch and update binary security patches for official releases. e.g. FreeBSD 9.0-RELEASE. Once you made fresh OS install this is the way to update your system quickly. freebsd-update fetch freebsd-update install Note, this tool doesn't work if you build world/kernel from source.

FreeBSD make.conf example

2012-08-18T19:00:00.000+03:00

make.conf stores system-wide build settings that apply each time you run make. Copy example: cp /usr/share/examples/etc/make.conf /etc Compile the source code specific to your CPU: CPUTYPE?=native It is recommended uncomment the following: CFLAGS, CXXFLAGS, COPTFLAGS. # 2 jobs per CPU MAKE_JOBS_NUMBER=4 # KNOBS -- A list of popular knobs and their descriptions # http://svn.freebsd.org/

How to setup HTTP Proxy in FreeBSD

2012-08-18T18:30:00.000+03:00

The HTTP proxy is set through environment variable HTTP_PROXY. Environment variables can be controlled during user login. Assuming the proxy is proxy.somewhere.net:3128 ensure the following in /etc/login.conf: :setenv=HTTP_PROXY=http\c//proxy.somewhere.net\c3128:\ Update login capability database: cap_mkdb /etc/login.conf Re-login and ensure it is properly set: env | grep HTTP_PROXY

How to SU with no password in FreeBSD

2012-08-18T18:00:00.000+03:00

You can allow user to switch to root account without password. You need to add user to wheel group: pw usermod john -G wheel and change pam policy (file /etc/pam.d/su): #auth requisite pam_group.so no_warn group=wheel root_only fail_safe ruser auth sufficient pam_group.so no_warn group=wheel root_only fail_safe ruser It is necessary