* doc/syntax/miscellaneous.rdoc: Added documentation for alias, undef,

  BEGIN, END.
* doc/syntax/modules_and_classes.rdoc (Constants):  Fixed unwrapped
  paragraph with trailing whitespace.
* doc/syntax/modules_and_classes.rdoc (Scope):  Added section pointing
  to alias and undef documentation.
* doc/syntax.rdoc:  Added link to miscellaneous section.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38853 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 61 insertions, 0 deletions

diff --git a/doc/syntax/miscellaneous.rdoc b/doc/syntax/miscellaneous.rdoc
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+= 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'
+