```Issue #16021 has been updated by Dan0042 (Daniel DeLorme).

shevegen (Robert A. Heiler) wrote:
> (Not the same, I know, but my point is mostly that the second usage is =

> much easier to understand from a glance alone.)

Then what about making them equivalent so it's easier to compare which is m=
ore understandable.

``` ruby
12.3456.floor(step: 0.0002)
```
versus
``` ruby
(12.3456 / 0.0002).floor * 0.0002
```

IMHO the intent of the first one is obvious even without reading the `floor=
` documentation (but of course YMMV). If you think the second one is more u=
nderstandable then my proposal has no leg to stand on.

Although as shyouhei pointed out, the pitfalls of float arithmetic mean tha=
t solving those pitfalls gives this proposal more value than just syntactic=
sugar alone.

----------------------------------------
Feature #16021: floor/ceil/round/truncate should accept a :step argument
https://bugs.ruby-lang.org/issues/16021#change-80061

* Author: Dan0042 (Daniel DeLorme)
* Status: Feedback
* Priority: Normal
* Assignee: =

* Target version: =

----------------------------------------
These rounding methods currently accept a number of (decimal) digits, but a=
more general mechanism would allow rounding to the nearest =BC, multiple o=
f 5, etc.
Equivalent to e.g. `((num / step.to_f).round * step)`

``` ruby
12.3456.floor(step: 0.2) #=3D> 12.2
12.3456.round(step: 0.2) #=3D> 12.4
12.3456.floor(step: 0.2) #=3D> 12.4
12.3456.floor(step: 0.2) #=3D> 12.2
```

IMHO this should also apply to Time#floor/round/ceil

``` ruby
Time.now.floor(step: 3600) #=3D> current hour
Time.now.round(step: 3600) #=3D> nearest hour
Time.now.ceil(step: 3600)  #=3D> next hour
```

We can also consider that instead of `:step` , `:by` might be quite readabl=
e.

``` ruby
12.3456.round(by: 0.2) #=3D> 12.4
```

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