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Date: Thu, 30 Apr 2015 09:21:40 +0900
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To: Nathan Bruer <nathanbruer@gmail.com>
Cc: Christoph Becker <cmbecker69@gmx.de>, Ryan Pallas <derokorian@gmail.com>, 
	Stanislav Malyshev <smalyshev@gmail.com>, "internals@lists.php.net" <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c2558ed796970514e616a5
Subject: Re: [PHP-DEV] Adding "numeric" type hint
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

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Hi Nathan,

On Thu, Apr 30, 2015 at 6:41 AM, Nathan Bruer <nathanbruer@gmail.com> wrote:

> This has been a big issue that I have ran into many times in the past for
> large framework projects, instead of building it out with "strict" types
> like: int, float, string, exc... It makes more sense to allow a user to
> define a psudo-type themselves which PHP will pass the arguments into to be
> "cleaned" by the user then let the function deal with the arguments.
>
> For example:
> function force_int($value){
>   return (int) $value;
> }
> function must_be_string($v){
>   if(!is_string($v)){
>     throw new Exception("Not String");
>   }
>   return (string) $v;
> }
>
> function foo(*force_int $val, *must_be_string $str){
>   // $val will always be an int if it ever gets here
>   // $str will always be a string if it gets here
>   echo $val, " ", $str;
> }
> foo("foo", "bar"); // returns '0 bar'
> foo("1", "2"); // returns '1 2'
> foo(1, 2); // fatal error because second argument threw exception
> foo(1, "2") // returns '1 2'
> foo("hi", 2) // fatal error because second argument threw exception
> foo("hi", "2") // returns '0 2';
>

I agree. Forcing type is headache and such check is useful.
The problem with this approach is overhead. I would like to resolve this in
2 ways.

 1. DbC - Check parameter types during development by DbC and make
sure all callee satisfies contract.
 2. True weak type hint - Make weak mode type hint truly weak. Accept
any form of the specified types.

Since we won't have DbC for PHP 7.0, I'll discuss only option 2.

function foo(int $i) {
  switch(gettype($i)) {
  case 'integer':
  case 'float":
     foo_numeric($i);
     break;
  default:
     // We don't want to accept gmp/string
     throw new Exception('Type error');
  }
}

Ideal solution would be DbC. Anyway, above example is a little more
efficient
than calling pseudo type checker functions (for now). Pseudo type checker
is useful and requires less code. I'm neutral to have it or not.

Regards,

--
Yasuo Ohgaki
yohgaki@ohgaki.net

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