#{茶男與藍牌} » Ruby

warning: toplevel constant XX referenced by YY::XX (review)

茶男 — Tue, 01 Nov 2011 00:43:33 +0000

When I try to move the Devise stuff into a module User::Devise and include it in class User, I got this warning ‘warning: toplevel constant Devise referenced by User::Devise’

Please see the code before and after for a solution.

Solution is to make User::Devise before you do the include for class User

Discover ActiveRecord: cast an object to specified class

茶男 — Fri, 28 Oct 2011 05:22:06 +0000

Can’t find anything about casting an instance to specified class? Of cause, in Ruby, there is no such concept that you need to cast an instance in most of the cases. But how about you need to? Here is the answer:

By using ActiveRecord::Persistence.becomes, you can easily cast it to specified class.

For example:

rails postgresql adapter options

茶男 — Mon, 17 Oct 2011 05:06:01 +0000

from http://ar.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/PostgreSQLAdapter.html :host - Defaults to “localhost”. :port - Defaults to 5432. :username - Defaults to nothing. :password - Defaults to nothing. :database - The name of the database. No default, must be provided. :schema_search_path - An optional schema search path for the connection given as a string of comma-separated schema names. This is backward-compatible with the :schema_order option. :encoding - An optional client [...]

trick using question mark in rails model

茶男 — Mon, 17 Oct 2011 04:54:25 +0000

p = Person.new p.first_name = 'Tian' p.last_name = nil p.first_name? # => true p.last_name? # => false

alternative usage of question mark in ruby

茶男 — Mon, 17 Oct 2011 02:16:04 +0000

>> ?A => 65

6 Ways to Run Shell Commands in Ruby

茶男 — Thu, 22 Sep 2011 05:02:22 +0000

from http://tech.natemurray.com/2007/03/ruby-shell-commands.html

Often times we want to interact with the operating system or run shell commands from within Ruby. Ruby provides a number of ways for us to perform this task.

Exec

Kernel#exec (or simply exec) replaces the current process by running the given command For example:

$ irb >> exec 'echo "hello $HOSTNAME"' hello nate.local $

Notice [...]

Pre-defined Variables

茶男 — Wed, 14 Sep 2011 12:17:48 +0000

Name Aliases Description $! $ERROR_INFO The exception information message set by the last ‘raise’ (last exception thrown). $@ $ERROR_POSITION Array of the backtrace of the last exception thrown. $& $MATCH The string matched by the last successful pattern match in this scope. $` $PREMATCH The string to the left of the last successful match. [...]

Demystifying Irb’s Commands

茶男 — Tue, 30 Aug 2011 11:50:52 +0000

from http://tagaholic.me/2009/05/11/demystifying-irb-commands.html

Irb is one of the most commonly used standard ruby libraries, yet most don’t seem to know much about it. I’ve lost count of the number of blog posts that explain some irb “tricks” or “secret” config options. This is the first in a series that aims to make irb less magical and more [...]

Exploring How To Configure Irb

茶男 — Tue, 30 Aug 2011 11:47:26 +0000

from http://tagaholic.me/2009/05/29/exploring-how-to-configure-irb.html#eval_history

In my last post we discussed irb’s commands. This post goes further into irb’s innards, exploring all of its configuration options.

Gettin Ready

For starters, I refer you to the pickaxe which has an excellent section on configuring irb. Also, this post assumes ruby 1.8.6 and irb 0.9.5, though it should apply to 1.9ers. Yes, I [...]

error: no such file to load — readline (LoadError)

茶男 — Tue, 30 Aug 2011 00:29:38 +0000

from http://rails3blog.com/2010/09/error-no-such-file-to-load-readline-loaderror/

I was getting this error trying to start the rails console: error: no such file to load — readline (LoadError). I’m using rvm, rails3, ruby 1.9.2, Ubuntu 10.04.

I tracked down redline in my ruby source ~/.rvm/src/ruby-1.9.2-p0/ext/readline and ran:

ruby extconf.rb
This let me know I was missing these two packages:

libncurses5-dev [...]