Event Publisher


Class of objects that delegate all method executions to a group of subscriber objects. Such objects behave like instances of Wrapper but delegate method invocations to a group of objects instead of a single one. This class is useful to implement event notification mechanisms or to let event notifications destined for a single object to be captured by many.

Like in the Wrapper class, only one single special method is used to spread the call event for all delegated methods of all publishers without creating temporary closures or any other kind of structure. However, this mechanisms only work for method calls done with the : operator. Again, similar to the Wrapper, the self parameter is properly replaced by the destiny object in every method call. The publisher object can also be invoked as a function or can receive key-value mappings (i.e newindex event). In such cases the same event is perfomed over the delegated objects. Such objects are stored in the publisher object with any valid table key.



Setup the special delegation method in order to delegate the execution of the method indexed to all objects stored in the publisher.
Delegates any key-value mapping performed on the publisher to the objects stored in the publisher.
Delegates calls performed on the publisher to the objects stored in the publisher.



File handler that outputs to two different files.

local Publisher = require "loop.object.Publisher"

file = Publisher{
	assert(io.open("errors.log", "w")),

file:write("This text is being written ")
file:write("into two files simultaneously.")

file:close() -- 'io.stderr' is now closed.

Copyright (C) 2004-2008 Tecgraf, PUC-Rio

This project is currently being maintained by Tecgraf at PUC-Rio.