Blog Posts
Extending Singletons
This morning, I was wondering about how to extend a singleton class such that
you could retrieve the new class when retrieving the singleton later. In
particular, Zend_Controller_Front
is a singleton, but what if I want to
extend it later? A number of plugins in the Zend Framework, particularly view
helpers and routing functionality, make use of the singleton; would I need to
alter all of these later so I could make use of the new subclass?
For instance, try the following code:
class My_Controller_Front extends Zend_Controller_Front
{}
$front = My_Controller_Front::getInstance();
You'll get an instance of Zend_Controller_Front
. But if you do the following:
class My_Controller_Front extends Zend_Controller_Front
{
protected static $_instance;
public static function getInstance()
{
if (null === self::$_instance) {
self::$_instance = new self();
}
return self::$_instance;
}
}
$front = My_Controller_Front::getInstance();
You'll now get an instance of My_Controller_Front
. However, since
$_instance
is private in Zend_Controller_Front
, calling
Zend_Controller_Front::getInstance()
will still return a
Zend_Controller_Front
instance — not good.
However, if I redefine Zend_Controller_Front::$_instance
as protected, and
have the following:
class My_Controller_Front extends Zend_Controller_Front
{
public static function getInstance()
{
if (null === self::$_instance) {
self::$_instance = new self();
}
return self::$_instance;
}
}
$front = My_Controller_Front::getInstance();
Then the any time I call getInstance()
on either My_Controller_Front
or
Zend_Controller_Front
, I get a My_Controller_Front
instance!
So, the takeaway is: if you think a singleton object could ever benefit from extension, define the static property holding the instance as protected, and then, in any extending class, override the method retrieving the instance.
exuberant ctags with PHP in Vim
One reason I've heard PHP developers use for adopting an IDE when developing is the ability to click on a class or function name and jump to the declaration. Sounds like magic, and it's definitely something I've desired.
One way I get around it is by adopting PEAR coding standards for naming my
classes. Since they define a one-to-one mapping of class name to the file
system (substitute the underscore character (_
) with the directory
separator), I can usually very quickly and easily open a class file,
particularly if I start in the base directory of the project install.
Today, however, I found exuberant ctags, a library which can be used to generate an index file mapping language objects to source files and the line in the source file where they are declared. Contrary to its name, it's not just for the C language; it currently supports 33 different programming languages, including PHP.
I decided to try it out on the Zend Framework core library today. At first run, it was pretty useful. However, it was only mapping classes, and, in addition, only those defined with the single word 'class' — abstract classes and interfaces were entirely left out. So, I looked into the documentation to see if I could change the behaviour.
And, being a Unix program, of course I could. First off, you can add functions to the items it indexes with a simple flag. Additionally, you can use POSIX regular expressions to refine what it searches.
I whipped up the following script to create my tags index:
###!/bin/bash
cd /path/to/framework/library
exec ctags-exuberant -f ~/.vim/mytags/framework \
-h \".php\" -R \
--exclude=\"\.svn\" \
--totals=yes \
--tag-relative=yes \
--PHP-kinds=+cf \
--regex-PHP='/abstract class ([^ ]*)//c/' \
--regex-PHP='/interface ([^ ]*)//c/' \
--regex-PHP='/(public |static |abstract |protected |private )+function ([^ (]*)//f/'
This script creates the tag index in the file $HOME/.vim/mytags/framework
. It
scans for PHP files recursively through the tree, excluding any files found in
a .svn
directory (I'm using a checkout from the subversion repository). The
file paths in the index are created relative to the tags file; this was
important, because if this wasn't provided, vim was unable to jump to the file,
as it couldn't find it. --PHP-kinds=+cf
tells it to index classes and
functions. Next, I've got three regular expressions. The first tells it to
match classes beginning with 'abstract class' as classes. The second tells it
to match interfaces as classes. The last is so that PHP 5 methods, which begin
with a visibility operator, to be matched as functions.
Once the index file is generated (it takes less than a second), all you need to
do in vim is tell it to load it: :set tags=~/.vim/mytags/framework
. At this
point, you can do all sorts of fun stuff. Place the cursor on a class name or
method name, anywhere in it, and hit Ctrl-]
, and you'll jump to the file and
line of its declaration; Ctrl-T
then takes you back. If you change the
invocation to Ctrl-W ]
, it will split the current window and open the
declaration in the new pane. (If you're familiar with how help works with Vim,
this should seem pretty familiar.)
One more reason to stick with Vim for your PHP editing needs. :-)
PHP decoding of Javascript encodeURIComponent values
Recently, I was having some issues with a site that was attempting to use UTF-8 in order to support multiple languages. Basically, you could enter UTF-8 characters — for instance, characters with umlauts — but they weren't going through to the web services or database correctly. After more debugging, I discovered that when I turned off javascript on the site, and used the degradable interface to submit the form via plain old HTTP, everything worked fine — which meant the issue was with how we were sending the data via XHR.
We were using Prototype, and in particular, POSTing
data back to our site — which meant that the UI designer was using
Form.serialize()
to encode the data for transmission. This in turn uses the
javascript function encodeURIComponent()
to do its dirty work.
I tried a ton of things in PHP to decode this to UTF-8, before stumbling on a solution written in Perl. Basically, the solution uses a regular expression to grab urlencoded hex values out of a string, and then does a double conversion on the value, first to decimal and then to a character. The PHP version looks like this:
$value = preg_replace('/%([0-9a-f]{2})/ie', \"chr(hexdec('\1'))\", $value);
We have a method in our code to detect if the incoming request is via XHR. In
that logic, once XHR is detected, I then pass $_POST
through the following
function:
function utf8Urldecode($value)
{
if (is_array($value)) {
foreach ($key => $val) {
$value[$key] = utf8Urldecode($val);
}
} else {
$value = preg_replace('/%([0-9a-f]{2})/ie', 'chr(hexdec($1))', (string) $value);
}
return $value;
}
This casts all UTF-8 urlencoded values in the $_POST
array back to UTF-8, and
from there we can continue processing as normal.
Man, but I can't wait until PHP 6 comes out and fixes these unicode issues…
Overloading arrays in PHP 5.2.0
Update: I ran into issues with the ArrayObject
solution, as there was a bug in PHP 5.2.0 (now fixed) with its interaction with empty()
and isset()
when used with the ARRAY_AS_PROPS
flag. I tried a number of fixes, but eventually my friend Mike pointed out something I'd missed: as of PHP 5.1, setting undefined public properties no longer raises an E_STRICT
notice. Knowing this, you can now do the following without raising any errors:
class Foo
{
public function __set($key, $value)
{
$this->$key = $value;
}
}
$foo = new Foo();
$foo->bar = array();
$foo->bar[] = 42;
This is a much simpler solution, performs better, and solves all the issues I was presented. Thanks, Mike!
svn:externals
I was recently working with someone who was using Zend Framework in their project. To keep things stable and releasable, he was doing an export of framework into his repository and checking it in. Since files change so much in the ZF project currently, instead of doing an rsync from a checkout into his own repository, he decided instead to delete the directory from the repository and re-add it everytime he was updating framework.
This seemed really inefficient to me, especially considering that it made it incredibly difficult to merge changes from his development branch into his production branch (deleting and re-adding directories breaks the merge process considerably). I knew there had to be a better way.
I'd heard of the svn:externals
property before, but never really played with
it. As it turns out, it exists for just this very type of situation. The
problem is that the documentation of svn:externals
in the SVN book doesn't indicate at all how the property should be set, and
most howto's I've read omit one or more very important details. I finally
figured things out through some trial and error of my own, so I'm going to
share the process so others hopefully can learn from the experience as well.
It's actually pretty easy. This assumes that your project layout looks something like this:
project/
branch/
production/
tag/
trunk/
-
In the top of your project trunk, execute the following:
$ svn propedit svn:externals .
-
This will open an editor session. In the file opened by your editor, each line indicates a different external svn repo to pull. The first segment of the line is the directory where you want the pull to exist. The last segment is the svn repo URL to pull. You can have an optional middle argument indicating the revision to use. Some examples:
-
Pull framework repo from head:
framework http://framework.zend.com/svn/framework/trunk
- Pull framework repo from revision 2616:
framework -r2616 http://framework.zend.com/svn/framework/trunk
-
-
After saving and exiting, update the repo:
$ svn up
-
Commit changes:
$ svn commit
One thing to note: any directory you specify for an svn:externals
checkout
should not already exist in your repository. If it does, you will get an
error like the following:
svn: Working copy 'sharedproject' locked
svn: run 'svn cleanup' to remove locks
I show using revisions above; you could also pin to tags by simply checkout the external repository from a given tag. Either way works well.
Then, when moving from one branch to another, or from the trunk to a branch,
you simply set a different svn:externals
for each branch. For instance, your
current production might check from one particular revision, but your trunk
might simply track head; you then simply determine what the current revision
being used is on your trunk, and update svn:externals in your production branch
when you're ready to push changes in.
Hope this helps some of you out there!
Getting XDebug working with PHPUnit for code coverage reports
I've been playing with PHPUnit a lot of late, particularly with framework development. One thing that's always hard to determine is how well your code is exercised — basically, how much of the code is tested in the unit tests?
In PHPUnit 3, you can now generate code coverage reports using XDebug, and the usage is very simple:
matthew@localhost:~/dev/zend/framework-svn/tests$ phpunit --report ~/tmp/report AllTests
The above command creates a coverage report directory report
under my tmp directory. You can then browse through the reports in a web browser and visually see which lines of code were executed during tests, and which were not, as well as a synopsis showing the percentage of coverage for any given file or directory — useful stuff indeed!
So, what's the problem? Getting XDebug running.
The executive summary:
-
Enable the extension using
zend_extension = /full/path/to/xdebug.so
, not asextension = xdebug.so
, in yourphp.ini
-
Use the setting
xdebug.default_enable = Off
in yourphp.ini
. -
If compiling using pecl or pear, make sure it compiles against the correct PHP; if not, hand compile it using:
$ /path/to/phpize $ ./configure --with-php-config=/path/to/php-config $ make $ make install
For the detailed narrative, read on.
MVC changes in Zend Framework
Several months ago, Andi asked me to take the role of lead developer on a refactoring of the Zend Framework MVC components. I agreed, though somewhat reluctantly; I already maintain another MVC library, and wasn't sure how well I could fill the shoes of people like my friends Mike, who had done the initial development on the controller classes, and Paul, who provided Zend_View
.
The experience has been incredibly rewarding, however, and I've had the chance to pick the brains of and work with some top-notch developers in the process. In the next week or so, we'll be releasing version 0.6.0 of the framework, and it will include much of my work in the MVC components as part of the core distribution. A big thanks to all those who have contributed opinions, design help, code, tests, and documentation; another thank you goes to Andi for trusting and supporting me in this endeavor.
So, what are the changes? Read on to find out…
PHP Best Practices
Yesterday, Mike and I presented our session "Best Practices of PHP Development" at this year's Zend Conference. It was a marathon three hour tutorial first thing in the morning, and we had an incredible turnout, with some fairly enthusiastic people in the audience.
ZendCon: Best Practices Session
As Mike already noted, he and I are presenting a session on "Best Practices of PHP Development" at this year's Zend Conference and Expo. It has been my fortunate experience to work with Mike in the past, and, as he noted, we had so much fun presenting during last year's conference, we thought we'd do it again.
The session is a pre-conference tutorial session, running for 3 hours on Monday morning, 30 October 2006. Currently, we're shaping up the session into the following subject areas:
-
Programming Practices
- Coding Standards
- Test Driven Development and Unit Testing
- Project Documentation
-
Tools and Processes
- Software Configuration Management (SCM)
- Collaboration tips and tools
- Deployment
Emphasis is going to be on working in teams, particularly those operating in geographically diverse areas. With roughly 30 minute blocks per topic, we've certainly got plenty to cover!
If you're coming to the conference, we look forward to seeing you in our session!
Zend_XmlRpc_Server
As noted previously by myself and Davey, I've been working on Zend_XmlRpc_Server
for some months now. In the past couple weeks, I've refactored it to push the class/function reflection into Zend_Server_Reflection
, and, in doing so, noted that there were further areas for refactoring into additional helper classes. Currently, it now has classes for the Request, Response, and Faults, and all actual XML wrangling is done in those, making the server basically XML-agnostic.