d-money ctor(string) has bug, be careful! EUR("1.23456") ==> ctor ==> 3.3456EUR

[mw]

Hi,

(if you are not a user of this package: 
https://code.dlang.org/packages/money

you can stop reading now.

I'm a D newbie, not sure if this the best place to send this 
alert, but this library package is about money and has a relative 
large user base:

Download Stats:

6 downloads today
122 downloads this week
966 downloads this month
9300 downloads total

I think it worth attention from a big audience group).


The issue found is here:

https://github.com/qznc/d-money/issues/11

----------------------------------------------------------------------------------------
$ cat m.d
/+dub.sdl:
dependency "money" version="~>2.3.1"
+/

import std.stdio;
import money;

alias EUR = currency!("EUR");

void main() {
   EUR x = EUR( 1.23456 );
   EUR y = EUR("1.23456");
   writeln(x);
   writeln(y);
   assert(x == y);
}

$ dub m.d
1.2346EUR
3.3456EUR
core.exception.AssertError at m.d(15): Assertion failure
----------------
??:? _d_assertp [0x52b005]
m.d:15 _Dmain [0x4dec36]
Program exited with code 1

The reason is pow10(x) doesn't handle negative x at all.

https://github.com/qznc/d-money/blob/master/source/money.d#L64

when called from

https://github.com/qznc/d-money/blob/master/source/money.d#L107

with x = -1

BTW, why use a recursive function instead of a simple loop to 
calc pow10?