The numeric types float, double, decimal, and int are sort of apples from the same tree and MDriven exposes ways to go from all numeric types to decimal. The operator is called toDecimal.

Sometimes, you may want to assign from one type to another like this:

self.PaymentMenuRequest.VatPercent:=vTypAvBiljett.BiljettPrisMoms

but you get an error like 998: In ":=", one of the arguments must conform to the other (Nullable<System.Double> and Nullable<System.Decimal> do not).

Solve like this:

self.PaymentMenuRequest.VatPercent:=vTypAvBiljett.BiljettPrisMoms.todouble

These are valid assignments, but you change precision and lose fractions when converting to simpler types:

self.SomeInt:=self.SomeDouble

self.SomeDouble:=self.SomeInt

self.SomeDecimal:=self.SomeInt

self.SomeDecimal:=self.SomeDouble.todecimal

self.SomeInt:=self.SomeDecimal

self.SomeDouble:=self.SomeDecimal.todouble

In OCL you can also use a lot of the operators from C#, which are automatically added to the OCL and EAL language.

For example

Decimal.create(5.4).ToInt32

Creates a decimal with the value 5.4 and then converts it to an 32 bit integer, losing the fraction .4 in the process.