[TYPO3-team-core-v5] Validation: should '123' be considered a valid float?

[Bastian Waidelich]

Karsten Dambekalns wrote:

Hi Karsten,

we've discussed this yesterday and I gave it another thought.
In type-safe languages like C#, the difference between float and int is 
very important. When you multiply two or more integers, the result will 
always be an int. Divisions always result in float numbers.

In PHP the whole thing behaves a bit weird:

var_dump(3 * 2)   => int(6)
var_dump(3 / 2)   => float(1.5)
var_dump(3.5 / 2) => float(1.75)

but:

var_dump(6 / 2)   => int(3)
var_dump(3.5 * 2) => float(7)
is_float(3.5 * 2) => TRUE
is_float(7)       => FALSE


> Imagine a "Weight Watchers" website. You need to enter your weight. The argument 
> has been assigned a "float" validator.
> 
> You enter  |  Valid?
>   87.5     |    Yes
>   68.0     |    Yes
>   100      |     No

I guess, in this example the usability of that website wouldn't be very 
good if the user wasn't allowed to enter "100". But if I do a bank 
transfer via online banking, I'm glad that "10000" is not a valid input 
for the amount ;)

An extended float validator might look like this (similar to Maltes 
proposal):

class Float extends F3::FLOW3::Validation::AbstractValidator {

	public function __construct($minDecimalPlaces = 0, $maxDecimalPlaces = 
NULL) {
		...
	}

	public function isValidProperty($propertyValue, 
F3::FLOW3::Validation::Errors &$errors) {
		...
	}
}

by default ($minDecimalPlaces = 0, $maxDecimalPlaces not set) the 
validator could just return

(string)$value === (string)((float)$value)

Otherwise you'd have to split the input into two pieces..

Bastian