# `Mutare.Decimal.ModeSwap`
[🔗](https://github.com/foxbenjaminfox/mutare_decimal/blob/v0.2.1/lib/mutare/decimal/mode_swap.ex#L1)

:decimal_mode_swap — swaps Decimal rounding and string-format mode atoms.

The family targets mode arguments whose legal value set is Decimal-specific:

    Decimal.round(num, places, :half_up)     # -> :half_down / :half_even
    Decimal.round(num, places, :ceiling)     # -> :floor
    Decimal.round(num, places, :up)          # -> :down
    Decimal.to_string(num, :normal)          # -> :xsd / :raw
    Decimal.to_string(num, :scientific, opts) # -> :normal / :xsd / :raw

A pipe stage is mutated as the call it stands for: `num |> Decimal.to_string(:normal)` gets
the `to_string/2` swaps.

To avoid duplicates with the drop families, swaps to a default mode are excluded where
dropping the argument produces an equivalent mutation. Mutare.Decimal.DefaultDrop drops
round/3's mode (equivalent to :half_up), and Mutare.Decimal.LimitsDrop drops to_string/2's
format (equivalent to :scientific). For to_string/3, LimitsDrop removes the trailing options,
not the format, so :scientific remains a swap target. Because :half_up is never a swap
target, it is not included in this family's variant labels.

# `variants`

```elixir
@spec variants() :: [atom()]
```

The target-mode labels accepted by qualified mutare ignore directives.

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*Consult [api-reference.md](api-reference.md) for complete listing*