Question

When writing a CRUD MVC application, would you suggest using arrays instead of long (even short) parameter lists when writing an api for your business layer (model)?

For instance, which would you suggest:

1

// Posts::getPosts(20, 0, $category, 'date_added');
static function getPosts($limit = NULL, $offset = NULL, Model_Category $category = NULL, $sort_by = NULL);

2

// Posts::getPosts(array('limit' => 20, 'offset' => 0, 'category' => $category, 'sort_by' => 'date_added'));
static function getPosts(array $options = NULL);`

1 seems a lot cleaner and less prone to bugs, but 2 seems WAY more flexible (can easily add/switch parameters without changing the api). Just looking for reasons to go either way.

Thanks

Answer 1

I go with this rule of thumb:

If

• there are more than 5 arguments
• there is no logical order of the arguments
• there is not a clear logical dependency between arguments
  and/or
• most of the arguments are optional

Then it is probably a good idea to use an array to simulate keyword arguments. Otherwise, just go with standard arguments.

Also, consider using a parameter object to do complicated method calls.

EDIT: What would I do with this?

public static function search(
  $keywords,
  $limit = NULL,
  $offset = NULL,
  Model_Post_Type $type = NULL,
  Model_Category $category = NULL
)

Well, with a parameter array (also known as keyword arguments in languages that support them, like Python), my personal preference would be to do this:

public static function search($keywords, $options = array()) {
  $default_options = array(
    'limit' => NULL,
    'offset' => NULL,
    'post_type' =>  NULL,
    'category' => NULL
  );
  extract(array_merge($default_options,$options));
  // search logic, using $keywords, $limit, $offset, $post_type, $category
}

This gives you a few benefits:

• Anything in $options is completely optional. Any required arguments should be arguments.
• Gives you complete control over the defaults of those options, even allowing for complicated expressions in the array initializer.
• Allows you to add new (optional) search options later on, while remaining backwards-compatible with existing code.
• extract() makes key-value pairs into variable-value pairs, so the rest of the method is completely oblivious to the fact you’re using a parameter array and not normal arguments.