On Tue, 2008-03-18 at 22:56 -0500, Shawn McKenzie wrote: > Ray Hauge wrote: > > I've been reading up on some of the parts of PHP that has been suggested > > could be improved so that I could be more well informed. One of the > > more "interesting" (for lack of a better word) suggestions is closures. > > I've used closures primarily in JavaScript, and they are handy in that > > context, but JavaScript handles events and other more dynamic situations > > like that. > > > > I can't really think of any good examples of why I'd want to use a > > closure instead of just calling functions or class methods in PHP. > > Variable functions and call_user_func*() have worked for any of the > > cases where I did need to be a bit more dynamic. > > > > I found a great summary of some discussion on the internals mailing list > > over here: http://devzone.zend.com/node/view/id/2013#Heading1 > > > > After reading that article through, I do like Wez's idea of how to > > create anonymous functions. The point about it causing confusion with > > people coming from other languages definitely applies though. This > > article also gives me a second idea for this post. How many people > > would want closures in PHP? > > > > In summary: > > > > Would you want closures in PHP, and why? > > > O.K. so I check wikipedia and read what a closure was :-) But what in a > simple sentence or two would is the benefit of a closure compared to how > you would get the same functionality in PHP now? I'm pro closures. Closures allow you to create anonymous functions that inherit the contextual environment (variables) without the need to specifically pass the environment (variables). That means within a class method context I don't need to pass the object to the function, nor do I need to pass any other variables that have been defined in the method. The closure can just use them as thought hey had been declared directly within it's own block. The same thing would happen within a function. This is very convenient. It goes beyond this though, if I create an anonymous function and assign it to a variable for later use, it still inherits the environment. Essentially this enables the environment to live on beyond the life of the original function in which the closure was created. This means I can specifically create an environment for functions/methods, then save off the closures to be run at a later point and they will retain all the information that was defined in the caller. Additionally, and unlike using an object instance, the environment is shared between all functions instantiated within the scope. One might argue that the same can be done with a singleton... and one would be correct. Similarly it can be done by pasing around a "singleton" array. The diffeence is that with a closure the data need not be passed around, it is part of the function's environment AND the environment is perfectly hidden from anyone receiving the function (it can't be probed (not normally anyways)). Cheers, Rob. -- http://www.interjinn.com Application and Templating Framework for PHP -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
