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Date: Wed, 10 Aug 2016 21:44:19 -0400
Message-ID: <CAEYWF=4kkvmp8TCmRhdhzzM-sWpk+-sYE7u2eP1Jf3NkshFiJA@mail.gmail.com>
To: Lester Caine <lester@lsces.co.uk>
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a113d7514507fab0539c1e937
Subject: Re: [PHP-DEV] Simple variable handling.
From: bishop@php.net (Bishop Bettini)

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On Wed, Aug 10, 2016 at 4:07 PM, Lester Caine <lester@lsces.co.uk> wrote:

> People keep complaining that I do not contribute any proposals to
> improve PHP, which to some extent s correct. Except the one thing that I
> keep trying to get a handle on is tidying validating of the basic
> variables that are the heart of PHP.
>
> validate_var_array() is a case in point, since ALL it should do is
> handle an array of simple variables for which we can define REAL
> validation rules rather than just a very restricted 'type' rule.
> Massaging the way the content of a variable is presented is another part
> of the basic functions of handling a variable, and simply providing an
> escape option which can be set as part of the variable rules set
> eliminates the need for 'New operator (short tag) for context-dependent
> escaping' and similar tangential matters. If we have a set of rules
> wrapping a variable then everything else just follows on, and the SQL
> domain model allows a group of variables to take an identical se of rules.
>
> These are the sorts of things any decent user world library can and does
> provide, but if the clock was rolled back prior to all the trouble
> created by 'strict typing' and we started again with a more well defined
> simple variable I'm sure that much of the conflict could have been
> resolved by allowing full validation checks to control an error or
> exception depending on the 'style' of PHP a programmer prefers.
>
> If a function is going to return a variable and that variable has under
> the hood a set of validation rules, then one can return an error if the
> result is faulty. Or even allow a NULL return if a valid answer is not
> available ... if that is the style of programming one prefers.
> Exceptions handle unmanaged errors, while proper program flow handles
> managed ones!
>
> Wrap these intelligent variables inside a class and one can create more
> powerful objects but ones which still use all the basic functionality.
> Similarly an array of them can be asked to provide a simple 'yes/no' if
> all of the variables pass their validation check, or an array of
> elements which need processing.
>

Do you mean attaching a functional validator to a variable, something like
this hypothetical code? (Note the 3rd argument to settype):

// $_POST['age']  = 27;
// $_POST['name'] = 'Sugah Pop';

try {
    settype($_POST['age'],  'int',    'is_int');
    settype($_POST['name'], 'string', function ($name) { return
strlen($name) < 255; });
} catch (\TypeError $er) {
    die($er->getMessage());
}

// ... Later:

$_POST['name'] = str_repeat('a', 1024);
// Throws \TypeError: "Invalid value set into variable in demo.php on line
14"

Or same idea, but used as "smarter" formal argument validators:

function do_something($age, $name) {
    settype($age,  'int',    'is_int');
    settype($name, 'string', function ($name) { return strlen($name) < 255;
});
    // $age and $name now have persistent validator rules attached to them
    // write operations onto the variable will assert the truth of the
    // validator before assigning. Obviously, there is a run-time cost.
}

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