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| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | doc/syntax/methods.rdoc | 32 |
2 files changed, 37 insertions, 0 deletions
@@ -1,3 +1,8 @@ +Tue Jan 15 11:49:31 2013 Eric Hodel <drbrain@segment7.net> + + * doc/syntax/methods.rdoc (Block Argument): Added section on block + argument. Thanks to Andy Lindeman. + Tue Jan 15 10:54:59 2013 Eric Hodel <drbrain@segment7.net> * doc/syntax/calling_methods.rdoc (Arguments): Added improved diff --git a/doc/syntax/methods.rdoc b/doc/syntax/methods.rdoc index 70a916387d..a86576c4a1 100644 --- a/doc/syntax/methods.rdoc +++ b/doc/syntax/methods.rdoc @@ -210,6 +210,38 @@ is raised. When mixing keyword arguments and positional arguments, all positional arguments must appear before any keyword arguments. +== Block Argument + +The block argument is indicated by <code>&</code> and must come last: + + def my_method(&my_block) + my_method.call(self) + end + +Most frequently the block argument is used to pass a block to another method: + + def each_item(&block) + @items.each(&block) + end + +If you are only going to call the block and will not otherwise manipulate it +or send it to another method using <code>yield</code> without an explicit +block parameter is preferred. This method is equivalent to the first method +in this section: + + def my_method + yield self + end + +There is also a performance benefit to using yield over a calling a block +parameter. When a block argument is assigned to a variable a Proc object is +created which holds the block. When using yield this Proc object is not +created. + +If you only need to use the block sometimes you can use Proc.new to create a +proc from the block that was passed to your method. See Proc.new for further +details. + == Exception Handling Methods have an implied exception handling block so you do not need to use |