PHP Methods – Should Utility Methods Be Inside a Class?

classfunctionsmethodsPHPstatic methods

I have been working on a library which contains a large set of functions. For the sake of simplicity, I am going to use just one set as an example.

I am not sure which is the better way, in terms of ease of use and performance, whether I should put those methods provided as individual methods, prepended with the function category, or whether it is better to create a Class containing all the method as static methods.

For Example:

Individual methods: (p.s. this could also be writen without request_ in the function name and using Namespaces instead)

function request_method() { ... }
function request_url() { ... }
function request_useragent() { ... }
....

Classed method:

class Request {
    public static function method() { ... }
    public static function url() { ... }
    public static function useragent() { ... }
    ...
}

Best Answer

The key is to put logically related functions in the same namespace. Prefixing as a "namespace by convention" is a bad idea. Depending on the language this has different meanings.

In a language like Java you have no choice you're going to have a utility class.
If you're in a language like Haskell, OCaml, or Python, these should be in a module.
In C++ you have namespaces for the same purpose.

By doing this you leave the burden of making sure you avoid naming clashes to your compiler. With prefixes you're liable to run into something like compiler_typecheck_ast. Does this refer to the class in the "namespace" compiler_typecheck or is it a function in the compiler namespace that typechecks an ast?

Related Solutions

Do Private Static Methods in C# Have Any Downsides?

I would think: "Do I need to test this?"

If your method is private anyway, meaning you don't want to unit test the logic in the method itself, then as far as testability and maintainability are concerned your class is a black box either way, the inner workings of your class are its business and its alone. Refactoring will not be affected either, which is also something to consider.

So, in my opinion: No, making a "private" method "private static" will have no long term ramifications whatsoever.

Static Method – Comparison with Instance, Class, Private, and Public Methods

I'm learning programming in Objective-C and I can't understand what a static method is.

Objective-C doesn't have "static methods". It also doesn't have private methods. It does have class methods (marked with a +) and instance methods (marked with a -). Class methods are similar to static methods in C++ in that you can call them without having an instance of the class that defines them, so I expect you're asking about class methods and why they're useful.

In Objective-C, classes themselves are a kind of object, and you can send messages to them just as you send messages to an instance of a class (although the messages that you can send are different). Class methods are used whenever you want the class to do something but don't have an instance of the class. They're often used for getting or creating instances of the class. A perfect example is the +alloc method. +alloc creates an instance of a class by allocating memory for that instance; it's then up to you to initialize the instance with an appropriate initializer:

Foo *f = [[Foo alloc] initWithBar:bar];

Here we're sending the message alloc to the object that is the Foo class itself in order to create an new instance of Foo. Then we're sending the message initWithBar: to the new instance in order to initialize it with the object bar.

Similarly, class methods are often used as "convenience constructors" to create an object in one step rather than the two above:

NSString *s = [NSString stringWithFormat:@"%f", someFloat];

Here we just send a message to the class NSString (remember, classes are themselves objects) and get back a properly initialized string.

Without class methods, there would be no way to create instances of classes.

Sometimes a class manages access to a shared instance of itself. In those cases, the class will often provides a method to retrieve that shared object:

NSFileManager *fileManager = [NSFileManager defaultManager];

Most of the time you don't need to create your own NSFileManager instance -- you can just use the shared object. Having the NSFileManager class manage that object makes sense -- it's easy to figure out how to get the shared instance, and the way the shared file manager is handled may change as the implementation of NSFileManager changes.

From what I read on Wikipedia, it sounds like a class method that can't access anything in self.

self is valid in a class method, but it refers to the class object and not to any instance of the class. So you're right that you can't access any instance variables from within a class method, but that doesn't mean that the message should be a "stand-alone function" entirely unrelated to the class.

Best Answer

Related Solutions

Do Private Static Methods in C# Have Any Downsides?

Static Method – Comparison with Instance, Class, Private, and Public Methods

Related Topic