Implementing from_decimal and to_decimal

[strzibny]

I think it would be nice and beneficial if there could be a way to accept Decimal on both input and provide on the output side. Many applications might be working or getting decimals and if then we want to use the money library it's kind of cumbersome. What do you think?

[Nitrino]

Hi @strzibny,

I think this is a great idea.
For input values, I think we can expand the capabilities of the parse function, now supported strings and floats.

Workaround for current functionality:

iex(7)> Decimal.cast(2.5) |> Decimal.to_float() |> Money.parse!()
%Money{amount: 250, currency: :USD}

I think to_decimal is a good name for the conversion function.

If you want to contribute, pull requests are welcome.

[strzibny]

Do you think that something like the following is fine for the reverse?

money_str = Money.to_string(money, separator: "", delimiter: ".", symbol: false)
{:ok, decimal} = Decimal.parse(money_str)

[Nitrino]

It's a working option, but it's better to work with numbers.

iex(17)> price = Money.new(25, :USD)
%Money{amount: 25, currency: :USD}
iex(18)> price_in_float = price.amount / Money.Currency.sub_units_count!(price)
0.25
iex(19)> Decimal.from_float(price_in_float)
#Decimal<0.25>

This will give the same result, but it will avoid unnecessary conversions and the math will not depend on formatting settings.

[strzibny]

@Nitrino yes, that would work better :)