Ah, you have run into the insufficiently well known "ScaledDecimal looks like what you need but isn't".
In VisualAge, you have a data type that is basically a reflection of iBM mainframe "packed decimal" format, and perfectly suits the needs of an SQL or COBOL interface. It gives you round-tripping with no error. In my Smalltalk, ScaledDecimal is a pair (n,s) where n and s are unrestricted integers, representing n * (10 raisedTo: s). This also gives you exact round-tripping and suits the needs of an SQL or COBOL interface. However, in Squeak and Pharo, ScaledDecimal is something else entirely. Basically, a pair (q,s) where q is an Integer or Fraction, and s is a scale factor used for *printing*. This doesn't just lead to oddities like two unequal ScaledDecimals printing identically, it leads to rounding issues. This is not a bug, it is ScaledDecimal working as designed. Working within Squeak, the simplest approach is to represent money as pence, and the next simplest is to make or find a Money class. On Tue, 31 Aug 2021 at 00:02, David Pennington <da...@totallyobjects.com> wrote: > > Hi everyone. I have a little bank analysis package for my own use but having > trouble displaying and storing amounts. I parse out a CSV file from the bank > and convert the amounts from text to ScaledDecimal. I then store these into a > STON file, which converts them back to text. I then read them in and convert > them back to ScaledDecimal again. > > I am not used to ~Pharo have spent 24 years using VisualAge Smalltalk so I > need a little bit of help because I am getting 1 Penny errors in the > conversions. I can cope with this but I would like to get it right. > > Can anyone give me a simple means of managing, say, an amount like £76.49 > from the bank so that it stops coming back to me as £76.48? > > David > Totally Objects
