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Diffstat (limited to 'railties/doc/guides/source/creating_plugins/core_ext.txt')
| -rw-r--r-- | railties/doc/guides/source/creating_plugins/core_ext.txt | 98 |
1 files changed, 0 insertions, 98 deletions
diff --git a/railties/doc/guides/source/creating_plugins/core_ext.txt b/railties/doc/guides/source/creating_plugins/core_ext.txt deleted file mode 100644 index cbedb9eaf2..0000000000 --- a/railties/doc/guides/source/creating_plugins/core_ext.txt +++ /dev/null @@ -1,98 +0,0 @@ -== Extending core classes == - -This section will explain how to add a method to String that will be available anywhere in your rails app. - -In this example you will add a method to String named `to_squawk`. To begin, create a new test file with a few assertions: - -*vendor/plugins/yaffle/test/core_ext_test.rb* - -[source, ruby] --------------------------------------------------------- -require File.dirname(__FILE__) + '/test_helper.rb' - -class CoreExtTest < Test::Unit::TestCase - def test_to_squawk_prepends_the_word_squawk - assert_equal "squawk! Hello World", "Hello World".to_squawk - end -end --------------------------------------------------------- - -Navigate to your plugin directory and run `rake test`: - --------------------------------------------------------- -cd vendor/plugins/yaffle -rake test --------------------------------------------------------- - -The test above should fail with the message: - --------------------------------------------------------- - 1) Error: -test_to_squawk_prepends_the_word_squawk(CoreExtTest): -NoMethodError: undefined method `to_squawk' for "Hello World":String - ./test/core_ext_test.rb:5:in `test_to_squawk_prepends_the_word_squawk' --------------------------------------------------------- - -Great - now you are ready to start development. - -Then in 'lib/yaffle.rb' require 'lib/core_ext.rb': - -*vendor/plugins/yaffle/lib/yaffle.rb* - -[source, ruby] --------------------------------------------------------- -require "yaffle/core_ext" --------------------------------------------------------- - -Finally, create the 'core_ext.rb' file and add the 'to_squawk' method: - -*vendor/plugins/yaffle/lib/yaffle/core_ext.rb* - -[source, ruby] --------------------------------------------------------- -String.class_eval do - def to_squawk - "squawk! #{self}".strip - end -end --------------------------------------------------------- - -To test that your method does what it says it does, run the unit tests with `rake` from your plugin directory. To see this in action, fire up a console and start squawking: - --------------------------------------------------------- -$ ./script/console ->> "Hello World".to_squawk -=> "squawk! Hello World" --------------------------------------------------------- - -=== Working with init.rb === - -When rails loads plugins it looks for the file named 'init.rb' or 'rails/init.rb'. However, when the plugin is initialized, 'init.rb' is invoked via `eval` (not `require`) so it has slightly different behavior. - -Under certain circumstances if you reopen classes or modules in 'init.rb' you may inadvertently create a new class, rather than reopening an existing class. A better alternative is to reopen the class in a different file, and require that file from `init.rb`, as shown above. - -If you must reopen a class in `init.rb` you can use `module_eval` or `class_eval` to avoid any issues: - -*vendor/plugins/yaffle/rails/init.rb* - -[source, ruby] ---------------------------------------------------- -Hash.class_eval do - def is_a_special_hash? - true - end -end ---------------------------------------------------- - -Another way is to explicitly define the top-level module space for all modules and classes, like `::Hash`: - -*vendor/plugins/yaffle/rails/init.rb* - -[source, ruby] ---------------------------------------------------- -class ::Hash - def is_a_special_hash? - true - end -end ---------------------------------------------------- |