Pinderkent

The recent 6 Signs of Adaptive PHP article gives some examples of different PHP coding techniques. Unfortunately, it only bothers to cover the supposed "benefits" of each, without any consideration of how such techniques can prove to be problematic.

The first technique suggests passing all arguments to a function within a single associative array. The supposed "benefits" all promote laziness, namely in that all parameters become potentially optional, and less or no change is needed to any invocations of the function if parameter changes are made.

Not mentioned in that article were the drawbacks. One obvious problem is the vastly increased verbosity, both when it comes to handling default values, and when it comes to invoking the function. Default parameter values, as offered by languages like C++ and even VB.NET, are syntactically superior to this approach.

Even the very concept itself is flawed, as it's much better in terms of maintainability and clarity to have an explicit list of parameters. For one thing, this technique makes it much less obvious to other programmers how to call the function. Given the general lack of documentation associated with most PHP applications, it's likely that anybody wishing to use the function would have to consult the code of the function itself. It also inhibits the ability of the interpreter to check that the correct number of arguments have been passed to the function.

Furthermore, if one has a function that has so many optional parameters that such a technique is needed, perhaps too much is being done in that single function. It would appear that such a function is a good candidate for heavy refactoring.

The second suggestion recommends checking for functions and classes before making use of them, such as those exposed by a plugin module. This sounds risky. When it comes to plugins, the host application should insist that any plugins conform to a strict API. Working with plugins that may just decide not to export a certain required function, for instance, is a recipe for disaster. If a plugin module doesn't provide the proper interface, it should not be loaded.

The third suggestion is perhaps the only one that's sensible. It suggests using require_once() to prevent multiple inclusions of some external PHP code. Indeed, this typically is a good idea.

The fourth suggestion recommends that associative arrays be used to return multiple values from a function. While this isn't as bad of an idea as the use of an associative array to store parameter values, this seems to indicate that PHP should offer a more lightweight construct such as the tuples found in languages like Python and Standard ML. Sticking with what PHP already offers, perhaps even an object could be returned, rather than an associative array.

The fifth suggestion recommends the use of an __autoload function. The very existence of this function suggests that PHP has some serious shortcomings when it comes to allowing for the sensible separation of code. On one hand, this sort of dynamic loading is the sort of functionality that PHP should offer transparently.

Furthermore, it indicates a laziness on the part of PHP developers who wish to write code making use of classes defined in other source files, but who are unwilling to put forth the small amount of effort needed to explicitly include such files.

In addition, the three notes in the __autoload documentation should make developers hesitant to use such functionality. It appears that it interferes with the semantics of exception handling, it's not available when using PHP in its interactive mode, and has risks associated with the validity of the class names passed to it. Frankly, it sounds like yet another PHP "bandage" meant to patch over problems in the language and programmer laziness, while at the same time introducing far more severe problems.

The final suggestion recommends that the directory of the script be determined by calling dirname(_FILE), especially for the purposes of location other PHP files to include. For the given example, the use of a relative path should be sufficient.

The PHP community has a long history of not fixing the problems with their language and its most common implementation. Far too often we've seen "solutions" like these, which end up being messier and more convoluted than had the problem with PHP itself just been fixed sensibly. It's no wonder that so many PHP Web apps are buggy, full of security holes and essentially unmaintainable; the language itself is inherently broken, the workarounds are just as broken and full of caveats, and together they result in nothing but problems.