https://github.com/will/switchbox

declarative ruby conditions
https://github.com/will/switchbox

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declarative ruby conditions

• Host: GitHub
• URL: https://github.com/will/switchbox
• Owner: will
• Created: 2008-08-14T04:33:27.000Z (over 17 years ago)
• Default Branch: master
• Last Pushed: 2008-08-22T05:34:45.000Z (over 17 years ago)
• Last Synced: 2025-04-05T03:27:25.365Z (12 months ago)
• Language: Ruby
• Homepage:
• Size: 75.2 KB
• Stars: 3
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
SwitchBox

=========

Will Leinweber – [blog](http://bitfission.com)

About

-----

SwitchBox lets you declare simple conditions and combine them into more complex conditions. These are used to decide which action to run.

The upshot is that messy if/elsif/else blocks are no longer necessary. All conditions are lazily evaluated and will only be ran once.

Conditions

----------

Conditions have a name and a block. They are only run when checking for which action to call, and their result is cached and only ran once. The block doesn't necessarily have to evaluate a boolean, but SwitchBox forces the result into a boolean value before caching.

    record = some_active_record_object

    

    box = SwitchBox.new

    box.condition(:saved) { record.save }

In this example, a condition named "saved" is created. Behind-the-scenes, you also get a "not_saved" condition.

Actions

-------

Actions are stored in the order they're declared, and the very first action to meet all of its conditions will be executed, and no others.

    # ... continuing from the above code

    box.action(:saved)     { render :text => "the record was saved!" }

    box.action(:not_saved) { render :text => "there was a problem" }

    box.go # will result in calling the first block

    

SwitchBox#go will look at the conditions for each action, and run appropriate action.

Alternate syntax

----------------

The above syntax is nice because you can pass the box around as needed, but for simple things, you can just do it all in one block

    SwitchBox.new do

      condition(:always_true) { true }

      action(:always_true) { puts "always printed" }

    end

    

In this case you don't need to call #go, it gets called at the end of the block.