Nicollet.Net

Jeff Atwood hates PHP. So do I—despite working with it on a daily basis and leading several interesting PHP-based projects to successful completion, I do find PHP to be a disaster in terms of language design, and despite its gradual improvements over the course of its evolution.

And yet, my biggest issue with PHP is the same I have with C and C++ and, arguably, every single language in the C family with the exception of JavaScript.

Some Examples

Consider a simple get-day-name function:

function french_day_name($timestamp)
{
  return array(
    "Dimanche", "Lundi",    "Mardi",   "Mercredi",
    "Jeudi",    "Vendredi", "Samedi"
  ) [(int)date('w',$timestamp)];
}

You feed in a timestamp, and you get the day’s name in French. It relies on the fact that array() is an array literal, which is an expression (you can assign it to a variable or pass it as an argument to a function) and [] subscripting can be used to extract a certain index from an array. Except that this doesn’t work because the syntax does not allow subscripting into an array literal. Contrast this with JavaScript :

function french_day_name(timestamp)
{
  return [
    "Dimanche", "Lundi", "Mardi", "Mercredi",
    "Jeudi", "Vendredi", "Samedi"
  ] [(new Date(timestamp)).getDay()];
}

This is what I call value consistency: if your semantics allow writing array[subscript], then I expect to be able to use an array literal (or any other expression that evaluates to an array) in that expression. As a matter of fact, I don’t know what kinds of expressions support subscripting in PHP, and that makes me feel insecure so I always assign my array to a variable beforehand.

The same happens in other situations as well. For instance, don’t expect to write (new Date(timestamp)) -> getDay() in PHP: there are restrictions on what kind of expressions are allowed on the left-hand side of the object member operator, too.

Also, don’t expect to write:

$obj -> random = $good_random ? 'mt_rand' : 'rand' ;

// Later

$obj -> random(); // Sorry, not a member function

($obj -> random)(); // Sorry, bad syntax

$rand = $obj -> random();
$rand(); // Good programmer, you get a twinkie

That’s right, there are restrictions on what kind of expressions can be used to call functions as well! At least JavaScript is sane about this.

Value Consistency

For consistency, every operation that can operate on an arbitrary value should have a syntax that lets the programmer specify that value as an expression, whether that expression is a literal, an identifier, or any complex expression that ultimately evaluates to an appropriate value.

There are no circumstances under which syntax alone should prevent an expression to be used in a context where another semantically identical expression can be used.