Blog on Rails: Ruby

Internet Explorer Worst?

Mon, 21 May 2007 10:34:05 GMT

Here is something I found while scanning ruby source code:

"Internet Explorer is the worst piece of crap to have ever been written, with the possible exception of Windows itself"

It was written as a string in the following files:

ruby\1.8\rexml\cdata.rb
ruby\1.8\rexml\comment.rb
ruby\1.8\rexml\doctype.rb
ruby\1.8\rexml\document.rb
ruby\1.8\rexml\element.rb

I know internet explorer is not as good as firefox, but c'mon its not that bad. Is it?

Automating Powerpoint with ruby

Fri, 23 Mar 2007 10:49:36 GMT

We know that ruby is a language of few words.
We can express a lot of things in a few words.

I was trying to export few slides in my powerpoint presentation to an image format using ruby.
I could not find any documentation for it anywhere except for a few basic things. But when I tried it by hit and trial I found out it to be surprisingly easy. It required just a few lines.

Here is what you have to do

----------------------------------------------------------------------
require 'win32ole'

begin
# open powerpoint
ppt = WIN32OLE.new('Powerpoint.Application')
# ensure it is visible
ppt.Visible = true
# open the presentation to be exported
pre = ppt.Presentations.Open("d:\\1.pptx")
# export the file
pre.Slides(1).Export("d:\\exp_file.png","png")
rescue
ensure
# close powerpoint, will close all the currently open files
ppt.Quit()
end
----------------------------------------------------------------------

Thats it. It is a full blown application. You can always use rmagick to further process this exported image.

Creating a User Interface in ruby ( Ruby playing nice with xaml )

Thu, 22 Mar 2007 11:35:19 GMT

There is a great gem 'rubyclr' that allows ruby to use .net code ie clr.

This gem can be installed with the command "gem install rubyclr".

Here I am going to present an example using that gem. It will be a simple application that will show how to trap xaml events using ruby.
So first you have to install the gem.

Then we will prepare the xaml file.
Its content would be:
--------------------------------------------------------------------------------------
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

<Grid x:Name="LayoutRoot">
<Button Margin="8,0,8,5.723" VerticalAlignment="Bottom" Content="Button" Name="the_button"/>
<TextBox Margin="8,8,8,38" Name="the_text_box"/>
</Grid>
</Window>
--------------------------------------------------------------------------------------
save this file as first.xaml
Note that we hve given names to both the controls as we will be using these names in our ruby code.

You can use notepad to mage this file or you can use microsoft blend which can allow to to may more fancy things.
There is a trial available for download. Its size is about 25 MB. For simple projects you can always use notepad.

Now we will create a ruby file to handle the events.
Its content would be:
--------------------------------------------------------------------------------------
# load the libraries
require 'rubygems'
require 'wpf'

# load the xaml file
window = XamlReader.Load(System::IO::File.open_read('first.xaml'))

# get the controls
button = window.find_name('the_button')
txt_box = window.find_name('the_text_box')

# trap the mouse enter event
button.mouse_enter do |sender, args|
txt_box.text += "MOUSE ENTERED\n"
end

# trap the mouse leave event
button.mouse_leave do |sender, args|
txt_box.text += "MOUSE LEFT\n"
end

# trap the mouse click event
button.click do |sender, args|
txt_box.text += "MOUSE CLICKED\n"
end

# run the application (most important)
Application.new.run(window)
--------------------------------------------------------------------------------------
save this file as first.rb

As you can see this file is preety much self descriptive. We just require the libraries, get the controls and handle the events.

Thats all to it. Just compile the ruby file using the command "ruby first.rb". Or if you dont you want the ugly dos window in the background you can use the command "rubyw first.rb"

Isnt that simple!

Finding classes dynamically in RUBY

Fri, 15 Sep 2006 17:50:54 GMT

Here is an update to this code making it even easier to find classes methods on the runtime.

class Called
def called_method
"string output"
end
end

class.rb

class Test
def calltest(clsname,methodname)
require clsname.downcase
puts eval(clsname.capitalize).new.method(methodname).call
end
end

Test.new.calltest('called','called_method')

caller.rb

ths output obviously is: string output

Awesome isn't it.

There are some restrictions link the class name must be same as the file name but still it does the job.

Older code

Today while writing a piece of code I needed to find a class by name. I haven't seen it in any other languages that I have programmed in but then if its ruby it might be possible.

Well its not only possible but really easy to implement.

Just look at the following piece of code.

class ClassName
def func
puts "I am output"
end
end

classname = 'ClassName'
cls = Kernel.const_get(classname)
obj = cls.new
obj.method("func").call

This example first finds a class then its method and in the last line executes it.

Really smooth isnt it.