Broken super strict on precision/scale policy

[DannyMeyer]

With every calculation operation where $scale can be provided, the super strict on precision/scale policy is beeing softened.

For example:

$decimal = new Decimal('123.123456');
$value = $decimal->add(0, 2);
var_dump($value->toString());

will result in

string(6) "123.12"

With the strict policy i would expect the InvalidArgumentException with the message: Loss of precision detected. Detected scale 6>2 as defined.

[dereuromark]

You are providing scale here as 2nd param, wouldnt that mean u want to set 2 as (min) scale here?

$decimal->add($int);

would do what you expect.

[InvisibleSmiley]

The documentation states:

Operations like add() use the higher of the scales of the operands.

So I would expect to have scale 2 be applied to "0" (resulting in "0.00") and "123.123456" to be the result.

In other words my intuition tells me that the scale parameter to "add" should be applied to the input rather than hinting at the output.

[InvisibleSmiley]

I guess some of the confusion stems from the fact that this lib uses bcmath internally (in this case bcadd) the operation of which is well-documented (https://www.php.net/manual/en/function.bcadd.php), while the API of this lib does not describe in detail what the parameters do (neither via PHPDoc nor Markdown documentation) right now.

I guess the first question to ask is what the lib methods are supposed to do, and IMHO that should ideally be self-explanatory rather than depending on people's expectations (which as we can see here vary). Then adapt the implementation, then the documentation.

[dereuromark]

A PR is welcome to clarify further
https://github.com/php-collective/decimal-object/tree/master/docs#precisionscale
states the basics so far afaik.