Re: [RFC] [Discussion] Support object type in BCMath

On 10 April 2024 00:36:21 BST, Saki Takamachi <saki@sakiot.com> wrote: >- The scale and rounding mode are not required for example in add, since the scale of the result >will never be infinite and we can automatically calculate the scale needed to fit the result. Does >adding those two options to all calculations mean adding them to calculations like add as well? That's why I mentioned the two different groups of users. The scale and rounding mode aren't there for group (a), who just want the scale to be managed automatically; they are there for group (b), who want to guarantee a particular result has a particular scale. The result of $a->add($b, 2, Round::HALF_UP) will always be the same as $a->add($b)->round(Round::HALF_UP) but is more convenient, and in some cases more efficient, since it doesn't calculate unnecessary digits. Remember also the title and original aim of the RFC: add object support to BCMath. The scale parameter is already there on the existing functions (bcadd, bcmul, etc), so removing it on the object version would be surprising. The rounding mode is a new feature, but there doesn't seem a good reason not to include it everywhere as well. >- As Tim mentioned, it may be confusing to have an initial value separate from the mode of the >round() method. Would it make sense to have an initial value of >HALF_UP? Again, the aim was to match the functionality of the existing functions. It's likely that users will migrate code written using bcdiv() to use BCMath\Number->div() and expect it to work the same, at least when specifying a scale. Having it behave differently by rounding up the last digit by default seems like a bad idea. Thinking about the implementation, the truncation behaviour also makes sense: the library isn't actually rounding anything, it's calculating digit by digit, and stopping when it reaches the requested scale. The whole concept of rounding is something that we are adding, presumably by passing $scale+1 to the underlying library functions. It's a nice feature to add, but not one that should be on by default, given we're not writing the extension from scratch. Regards, Rowan Tommins [IMSoP]