Paramater Passing

Date:    Wed, 19 Jul 1995 05:52:37 GMT
From:    "Glenn M. Picher" <gplists@IBM.NET>
Subject: Re: parameters to write just one function
The general technique is called "parameter passing": theSprite is a parameter passed from your on enterframe handler.

You can verify the correct type of parameters with code like ... 

  if not integerP(theSprite) then
    alert "theSprite is supposed to be an integer"
    return
  end if
Also, you can act on parameters and return a value to the calling function. 
  on squared(theNumber)
    return (theNumber * theNumber)
  end

  put squared(2)
  -- 4
  set theResult to squared(2)
  put theResult
  -- 4
Finally, you can also pass a varying number of parameters and detect them with the paramCount and param() keywords. 
on multiplyAll
  if (voidP(the paramCount) or (the paramCount <= 0)) then
    alert "multiplyAll is supposed to be supplied numbers to multiply!"
    return void
  end if
  put 1.0 into theResult
  repeat with i = 1 to the paramCount
    if not (integerP(param(i)) or floatP(param(i))) then
      alert "multiplyAll's parameter " & string(i) & " isn't a number"
      return void
    end if
    set theResult to theResult * param(i)
  end repeat
  return theResult
end


-  Glenn M. Picher   gpicher@ibm.net   gmpicher@pilot.njin.net
-  Roving multimedia programmer/artist; voice mail 502/745-0365
-  Replies go to gplists@ibm.net     Use gpicher@ibm.net for personal mail