Is it possible to write strictly typed PHP code?

Question

For example, is it possible to write code like this:

int $x = 6;
str $y = \"hello world\";
bool $z = false;
MyObject $foo = new MyObject();

Answer 1

Something you might try in order to simulate a poor man's strict type checking is using assert() to force the output to be of a particular type before you return it:

/**
 * Get Balance
 *
 * @return int
 */
function getBalance()
{
    /* blah blah blah */
   $out = 555; //Or any numeric value
   assert('is_int($out)');
   return $out;
}

So you keep your assertions active all throughout development and testing, sort of like the checks the compiler does at compile-time.

Granted, the assert() page is keen to assert that you shouldn't use assertions to check input parameters, but rather use normal conditionals to check them.

This answer had what I thought was a good rule:

The rule of thumb which is applicable across most languages (all that I vaguely know) is that an assert is used to assert that a condition is always true whereas an if is appropriate if it is conceivable that it will sometimes fail.

If you're simulating strict type-checking (writing your code to viciously maintain types; not trying to validate input from the outside), then you ought to be certain what the type is unless you've made a mistake.

Update:

There's also this: http://hacklang.org/ Facebook's PHP-based language with static typing.