Using A_screenHeight etc as optional parameters?

[PuzzledGreatly]

I tried to create a function starting as follows:

Code: Select all

CalcFontSize(txt,fWd:=A_screenWidth,fHt:=A_screenWidth)

but got this error message:

Line Text: CalcFontSize(txt,fWd:=A_screenWidth,fHt:=A_screenWidth)
Error: Unsupported parameter default.

How to use A_screenWidth and A_ScreenHeight as optional parameters or is it impossible? Thanks.

[PuzzledGreatly]

As soon as I posted I found an answer:

Code: Select all

CalcFontSize(txt,fWd:=0,fHt:=0)
{ 
  if fWd = 0
  fWd := A_screenWidth
  if fHt = 0
  fHt := A_screenHeight

But is there a better way?

[Coco]

Code: Select all

fn(w:="A_ScreenWidth", h:="A_ScreenHeight") {
	if (w == "A_ScreenWidth") ; if w is not  number
		w := %w%
	if (h == "A_ScreenHeight") ; if h is not number
		h := %h%
	MsgBox, % "Width: " w "`nHeight: " h
}

fn()

[PuzzledGreatly]

Thanks, that's an interesting alternative.

[Wade Hatler]

I program in one other language that allows you to use expressions as optional parameters. It's a very cool feature, although in practice I don't use it as much as you would think - maybe 2-3% of my functions. The technique shown above works well.

What I usually do is reserve a special word like NADA to mean that the paramter wasn't passed, and compare to that. Using 0 or blank doesn't work because quite a bit of the time you actually want to pass a zero or blank as the real value. So I'd code your function as:

Code: Select all

    CalcFontSize(txt,fWd:="NADA",fHt:="NADA") {
        fWd := (fWd != "NADA" ? fWd : A_ScreenWidth)
        fHt := (fHt != "NADA"  ? fHt : A_ScreenHeight)

Of course, in cases where 0 is never a valid answer, you can simplify it to something like:

Code: Select all

    CalcFontSize(txt,fWd:="",fHt:="") {
        fWd := (fWd ? fWd : A_ScreenWidth)
        fHt := (fHt ? fHt : A_ScreenHeight)

[PuzzledGreatly]

Thanks for the suggestion about NADA, you raise a good point about passing zero and genuine blank values.