From: "John W. Long" <ng@...>
Date: 2003-12-18T14:10:49+09:00
Subject: Re: Configuration Files

----- "Zach Dennis" wrote: -----
> What type of environment would you think something like this would apply
to?
>
> I dont' know what the "previous concept" was and it is hard for me to get
a
> good grasp in your post. Please help me understand. =) Thanks,

If you have ever found yourself storing configuration information in a ruby
file setting a bunch of global constants:

$TOOLBAR_VISIBLE = true
$TOOLBAR_CAPTION = "My Toolbar"
. . .

and then requiring your 'configuration.rb' into your main program you might
consider replacing your current constant based configuration with a file
like this:

toolbar.visible = true
toolbar.caption = "My Toolbar"

You can then read it into your program like this:

require 'config.rb'

$conf = Config.new

# define the structure of your configuration object
# and the default values for your configuration.
$conf.define %{
    menu.visible = true
    toolbar.visible = false
    toolbar.caption = "Tools"
    statusbar.visible = true
}

# we have defined the initial values of our Config object
# so we can now use them:
puts $conf.toolbar.visible.value #output: false
puts $conf.toolbar.caption.value #outputs: "Tools"

# most people will want to override the default values
# with something of their own, so we will read in the
# default values from our configuration file:
text = ''
File.open('myprogram.conf', 'r') { |file| text = file.read }
$conf.read text

# we just read in the values from our configuration file
# so we can now use them:
puts $conf.toolbar.visible.value #outputs: true
puts $conf.toolbar.caption.value #outputs: "My Toolbar"

# the rest of our program follows
. . .

I hope this is easier to understand than the last example. Let me know if
something is still not clear.

___________________
John Long
www.wiseheartdesign.com