$arg = $arg + array('hoho' => 'default value 1', 'hehe' => 'default value 2');

You know that you can do union like this, right ? If not, read the PHP manual again:

http://php.net/manual/en/language.operators.array.php

1. Using an associative array is fine, but remember that functions are APIs. If you’re working on a project with others, you’ll want them to find out the arguments and datatypes for those arguments by looking at your function definition. You lose this clarity when you clump everything into an associative array. There are uses for this, just not everywhere.

3. Definitely a good tip. A minor caveat is that require_once() is slower than require() since it needs an additional hash lookup to see if the file has been included before.

4. Again, similar drawbacks to #1, since now any changes you make to the returning associative array has the potential to break code that’s relying on the returned variables.

PHP is a great flexible language with a lot of power. But with that power comes responsibility to stick to best practices (and break them only in special circumstances).

If you’re talking about having adaptive PHP, you should really encourage your followers to define a storage array so they can dynamically store variables using __get and __set.

$merged = array_merge($vars, $args);
extract(array_intersect_key($merged, $vars));
unset($merged, $vars);
//code rest of function …
}

$defaults = array(‘hehe’ => ‘default hehe’, ‘hoho’ => ‘default hoho’);

$args = array_merge($defaults,$args);

This avoids a long list of isset or empty checks for all params.

As for point 3, this is solved through a sane include strategy, such as bootstrapping, that better structures your code. If you find yourself getting errors because you include the same file more than once, that’s a code smell, and a sign you need to reconsider your organization.

Using key/value pairs without discipline is a good way to turn an interface into mush.

Using autoload is dangerous and should never be undertaken without knowing what you’re doing — an example as simple as the one here should never be used.

Likewise with introspection — it’s a great idea but if you try to do anything as simple as the exists() examples here you’re going to dig yourself some huge holes and create some very _interesting_ bugs.

$arr = array();
$arr['param'] = null;
if ( isset($arr['param']) ) {
//do something
}

isset() will return false – even though the key does exist. If $arr['param'] is false, 0, ” (empty string), isset() will return true.