I’ve been working hard on Goodsie.com lately trying to bring it to launch. It’s been great being in on a new PHP project from (near) the beginning, as it frees up a number of things.
One of those, is the fact that I can be using PHP 5.3 and all the new features that come with PHP 5.3. While I’ve used my fair share of the short-cut ternary already (?:), the bigger win for me, are the Lambda functions with scoping (anonymous functions).
I found a very specific use out of the blue of Lambda functions that I have now used and I see as a great use-case. Which is specifically passing functions/logic from your Controller to your View.
In the case of Goodsie, I’m using PHP for my templating language and as usual I’m trying to remove as much logic from my View as possible, while still allowing the view to be malleable.
The specific case I had, was a subview that was generating some pagination code for me. You know, the standard ‘previous, page 1, page 1, next’ section of links. The basic HTML template I had, looked looked similar to:
<div class="pagination"> <a href="<?= $baseurl . '/page:' . ($page - 1) ?>">← Previous</a> Page <?= $page ?> of <?= $total ?> <a href="<?= $baseurl . '/page:' . ($page + 1) ?>">Next →</a> </div>
Rather straight forward, but I quickly ran into a problem. The way it worked, as you see, is that you passed in a base URL, and the page number you are currently on, and it generated appropriate forward/back links. (Ok, there was also some other logic where it determined if you needed the prev/next links at all, but I’ve removed that for clarity)
But then the solution dawned upon me. A lambda function would work admirably here. So what I did, is inside of my controller I created a function on the fly, that would generate the appropriate type of link that I was wanting. It looks something like:
Now I could simply rewrite my original template, to use this lambda function
$url to generate it’s URLs.
<div class="pagination"> <a href="<?= $url($page - 1) ?>">← Previous</a> Page <?= $page ?> of <?= $total ?> <a href="<?= $url($page - 1) ?>">Next →</a> </div>
Now not only would this work for my specific situation, but ANY controller could reuse this pagination subview and define exactly how it wanted it’s URLs to be formed. Now, the view could completely change around how the pagination section is displayed, show as many, or as few pages as it wants to, and all that without ever touching the controller.
This is one simple example, but I’ve become enamored of this approach. Using lambda functions in this way, you are able to have complicated logic represented inside of your view, but encapsulated/created by the controller. Also of note is the fact that the view is managing to use the
$baseurl values, but without actually having to be granted access to them. This allows for another level of encapsulation, as I exposed one function, instead of 2 separate variables. In the future if other data points start being needed to determine what a URL should be, the view never needs know that, as the controller will continue to update the function on it’s behalf.