> When `BcMath\Number` was introduced it allowed `string|int` method > arguments. According to a separate RFC to allow `int` to the functions this > was done as a performance optimization. Unfortunately this also means it > effectively disallows `float` types because PHP will truncate them to > integers (and emit a deprecation report) instead of preserving them as > strings. > > Example: https://3v4l.org/Bi5Kl > > ```php > var_dump( > (string)new BcMath\Number(5)->sub(4.2, 1), > bcsub(5, 4.2, 1), > ); > > string(3) "1.0" > string(3) "0.8" > ``` > > Per SakiTakamachi: > > If there is strong demand for creating the object from a `float`, it would > > be better to add support for `float` rather than removing `int` from the > > signature. > > As with the bc functions, converting a `float` to a `string` can be easily > > handled within php-src. > > > > In any case, discussion on the mailing list is necessary. > > > I was hoping to be able to use Number as a drop-in replacement for various > operations, especially back-of-the-napkin calculations, but this behavior > makes it too easy to accidentally write `$number * 1.2` and get unexpected > results. > > There are many arguments that could be made that float is the wrong type, > that it has rounding issues, and possibly other edge cases, but in the vast > majority of cases `(string)$float` does exactly what is expected. The lack of > a non-float decimal numeric type doesn't leave much room for native > expression short of doing `Number((string)$i) * Number((string)$j)` or > `Number('1.2') * '1.2'`. > > The expectation is that in PHP 9.0 float-to-int will be disallowed and would > automatically drop back to float-to-string in this case, but that is still a > long way away and would mean being unable to recommend using Number in 8.4, > 8.5, and beyond. > > Request context and discussion: > https://github.com/php/php-src/issues/18674 > > BcMath\Number RFC: > https://wiki.php.net/rfc/support_object_type_in_bcmath > > bcmath function int type RFC: > https://wiki.php.net/rfc/allow_int_args_to_bcmath_function
Hi Russell! As I already mentioned in the issue thread, I want to clarify just in case: even if we allow `float` as an argument, the internal behavior would essentially be the same as passing `(string) $float_num`. In fact, implementing any kind of custom conversion logic should be avoided, as it could lead to inconsistencies with PHP’s native casting behavior. Also, even if implicit casting behavior changes in PHP 9.0, please note that this would not benefit methods when `strict_types=1`. Personally, I chose not to accept `float` in the method signature because I prioritize the precision of BCMath. To be honest, I’m curious about how much demand there actually is for this kind of feature. Regards, Saki
