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Diffstat (limited to 'doc/syntax/miscellaneous.rdoc')
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diff --git a/doc/syntax/miscellaneous.rdoc b/doc/syntax/miscellaneous.rdoc new file mode 100644 index 0000000000..409afc797b --- /dev/null +++ b/doc/syntax/miscellaneous.rdoc @@ -0,0 +1,61 @@ += Miscellaneous Syntax + +== +alias+ + +The +alias+ keyword is most frequently used to alias methods. When aliasing a +method you can use either its name or a symbol: + + alias new_name old_name + alias :new_name :old_name + +For methods, Module#alias_method can often be used instead of +alias+. + +You can also use +alias+ to alias global variables: + + $old = 0 + + alias $new $old + + p $new # prints 0 + +You may use +alias+ in any scope. + +== +undef+ + +The +undef+ keyword prevents the current class from responding to calls to the +named methods. + + undef my_method + +You may use symbols instead of method names: + + undef :my_method + +You may undef multiple methods: + + undef method1, method2 + +You may use +undef+ in any scope. See also Module#undef_method + +== +BEGIN+ and +END+ + ++BEGIN+ defines a block that is run before any other code in the current file. +It is typically used in one-liners with <code>ruby -e</code>. Similarly +END+ +defines a block that is run after any other code. + ++BEGIN+ must appear at top-level and +END+ will issue a warning when you use it +inside a method. + +Here is an example: + + BEGIN { + count = 0 + } + +You must use <code>{</code> and <code>}</code> you may not use +do+ and +end+. + +Here is an example one-liner that adds numbers from standard input or any files +in the argument list: + + ruby -ne 'BEGIN { count = 0 }; END { puts count }; count += gets.to_i' + |