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Date: Thu, 11 Aug 2016 14:51:18 +0100
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Subject: Re: [PHP-DEV] Simple variable handling.
From: rowan.collins@gmail.com (Rowan Collins)

On 11/08/16 13:50, Niklas Keller wrote:
>> > If not by using exceptions, how would you handle them if you assign such
>> > checks to variables and assign a wrong value?

On 11/08/2016 14:29, Lester Caine wrote:
> if ( !$age->set( $result_set['age'] ) ) { // handle error }
> else { // next step }

So, cutting out the commentary about styles of coding, the answer to 
Niklas's question is "I would replace the assignment with a function or 
method that returned success based on validation result"?

To combine some of your examples:

// Set up the constraints:
$age->setannot( 'number', range(1,120) );

// Later:
$valid = $age->set( 'not a number' );
// or:
$age = $result_set['age'];
$valid = $age->is_valid();


This would result in $valid being false, but $age presumably still being 
the string 'not a number'? Or perhaps still being null, as though the 
assignment hadn't happened?

It seems like it would be more useful if the user didn't have to 
remember to call is_valid() on each variable before using it. That means 
having either the write operation, or subsequent read operations "fail" 
in some way.

$age_at_next_birthday = $age + 1; // reads from $age; is $age valid?

Throwing exceptions is a way of making operations like this "fail", 
rather than propogating the bad data to other parts of the program.

Does this look like the kind of thing you were imagining?

Regards,
-- 
Rowan Collins
[IMSoP]