H.2  Passing Simple Parameters to Routines

Sheerpower routines can have zero to 16 parameters. Parameters are always passed by name. There are two types of parameters: 1) those passed into the routine, and 2) those that are returned from the routine. Routines can also be called without any parameters at all. This is typical for global routines. Private and scoped routines tend to always have parameters.
Here is an example of a routine that calculates tax. We will pass into it an amount and a tax rate. It will return the tax due.

profit = 1234
tax_rate = 6.5/100
calculate_tax_due with amount profit, rate tax_rate, returning due tax_due
print 'Tax due: '; tax_due

private routine calculate_tax_due with amount, rate, returning due
  due = amount * rate
end routine

The with clause contains the names of the parameters coming into the routine. The returning clause contains the names of the parameters returned by the routine.

There can be up to 16 parameters in the with clause and up to another 16 parameters in the returning clause. From a maintenance standpoint, it is recommended to keep the number of parameters to just a few. If you need to pass in or out a lot of data, use cluster parameters (see next tutorial).

Simplified routine parameters
When passing parameters to routines, often there is a pattern of coding:

myamount = 45
myrate = 5.6

calculate_tax_due with amount myamount, rate myrate, returning due mydue

private routine calculate_tax_due with amount, rate, returning due
  due = amount * rate
end routine

Instead, we could use this code:

amount = 45
rate = 5.6
calculate_tax_due with amount amount, rate rate, returning due due

and even further simplify it as:

amount = 45
rate = 5.6
calculate_tax_due with amount, rate, returning due

The examples produce equivalent results where the last example is the simplest.