Return type hints View as Markdown

Hello ladies and gentlemen,

I made a patch that implements an experimental return type hint,
therefore we need discuss much about this yet, right? :)

My idea uses (php-type) and +className as notation, see below.

• PHP types

function (string) foo(...) { } // Unicode string too
function (object) foo(...) { } // Strict
function (array) foo(...) { } // Strict
function (bool) foo(...) { } // Strict
function (int) foo(...) { } // Accepts numeric string
function (double) foo(...) { } // Accepts numeric string

:: Question ---------------------------

• Add (resource), (unicode), (void) ? |

• Userland types (like actual parameter type-hint)

function +className foo(...) { }
function +interfaceName foo(...) { }
// Uses the class/interface 'int', not the type
function +int foo(...) { }

:: Question ----------------------------

• Weird syntax? |

:: Examples ------------------------------------------------

interface Itest { }
class bar implements Itest { }
class foo extends bar { }

class test {
static public function +Itest testing($instance) {
return $instance;
}
}

test::testing(new bar);
test::testing(new foo);
test::testing(new stdclass); // Error!
// Catchable fatal error: The returned value must implement interface
Itest

class foo {
public function +self getInstance() {
return $this;
}
}

$test = new foo;
var_dump($test->getInstance()); // OK!

object(foo)#1 (0) {
}

Finally, it's nice or poor syntax?

What must be improved/changed? (All?)

Patch: http://felipe.ath.cx/diff/return_type_hint.diff
Tests: http://felipe.ath.cx/diff/tests/

--
Regards,
Felipe Pena.

Em Seg, 2008-04-07 às 01:32 -0700, kalle@zesix.com escreveu:

:: Question ----------------------------

• Weird syntax? |

---

The syntax with the type casting seems abit weird as I've wrote above, I
would suggest perhaps making each datatype name a reserved keyword, eg.
int, integer, bool, bolean ect.

I really tried avoid this.
This is the reason for two notations.

--
Regards,
Felipe Pena.

Yes it does, and not only for VB developers.
I'm plain PHP developer (with some small Pascal and Delphi background) and I
faced quite a lot situations when named parameters would give me a lot. In
stead had to write some nasty code like

myFunc($param1, $param2, array(), null, $paramX);
myFunc($param1, array(), $param4, $param5, $paramX);

And it wasn't a matter of placing function params in right order - I was
just impossible. Actual alternatives were in writing functions wrappers or
write specialized functions witch were doing the same taks, just didn't made
checks for params.

2008/4/8, Richard Quadling rquadling@googlemail.com:

I think type hint's would be good optional functionality. Those who need
will use it, others will not. I'd probably use it in some cases.
Especially
if named parameters are implemented.

Sometimes what I really want is named parameter pass like

function myfunc(array $array, string $string = null, int $someint = 0){
}

myfunc($myArray, someint = $mySomeInt);

I think Named Parameters would be nice for VB developers.

It makes a LOT of sense to have this I think.

Christian Schneider

We have 2 possibilities.

• Throw an error
• Make type conversion

What to select is PHP developers team prerogative.

About example - that's MySQL who is very tollerant, other databases may not
threat well things like passing an ID to numeric field as string. That's bad
style to me. If you have a numeric filed - pass numeric values. If you have
character field - please pass strings. That's more like coding style and
isn't related to this disscussion. And if you have a type-hinted language,
then your ID will be integer anyway or your programm will segfault if you
try to assing a string to int type variable.

We are not talking about MySQL's capability to convert types itself and type
hinting isn't related only to databases - i just took first example I could
think of.

About conversions - see how PHP converts types - that's written in the
manual
echo (int)42; -> 42
echo (int)"42foo"; -> 42
echo (int)"foo"; -> 0
echo (int)"foo42"; -> 0

At least on bad ID's like "foo" or "foo42" you will have 0 and usualy there
are no ids with value 0 in databases, so you will get "No data avaliable" -
that's my approach witch proved to be good one over the years.