Variables referring into functions/subs

[David McFarlane]

Not sure I quite follow this, but why not just pass the variable of 
interest directly instead of merely passing its name as a String?  (I 
might also ask why you resort to using Canvas this way in the first 
place, but that is another issue.)  Using your example,

In global User Script:

     Sub CanvasInit( cnvs as Canvas )
         cnvs.FillColor = CColor("white")
         cnvs.TextColor = CColor("black")
         cnvs.Clear
     End Sub  ' CanvasInit()

In InLine:

     Set cnvs = Display.Canvas
     cnvs.Text Display.XRes, Display.YRes, "Hello, World!"
     Sleep(500)
     CanvasInit cnvs
     cnvs.text Display.XRes, Display.YRes, "Hello, Sam!"
     sleep(500)

Note the lack of parentheses around the argument in the call to 
CanvasInit -- unlike rational programming languages like C or MATLAB, 
in E-Basic/VBA arguments to Functions *must* be enclosed in 
parantheses, while arguments to Subroutines must *not* be enclosed in 
parantheses.  (Rational programming languages also make no hard 
distinction between functions & subroutines, but again, that is 
another matter.)

-----
David McFarlane
E-Prime training 
online:  http://psychology.msu.edu/Workshops_Courses/eprime.aspx
Twitter:  @EPrimeMaster (https://twitter.com/EPrimeMaster)

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At 12/26/2012 06:40 PM Wednesday, sam wrote:
>Hello!  I'm working on some experiments for the lab in which I 
>work.  I've run into some problems in the coding side, and I hoped I 
>could find some help here.
>
>I'm having some problems with variables.  I'll make up an example, 
>where I'm attempting to pass a string into a function.  I want to 
>use the contents of this string as a the name of any canvas I 
>choose, so I can clear any canvas by sending it's name into this subroutine.
>
>*****
>
>'userscript
>dim canvas as slide
>
>Sub clearcanvas(namecnvs as string)
>         Set namecnvs = Display.Canvas
>         namecnvs.FillColor = CColor("white")
>         namecnvs.TextColor = CColor("black")
>         namecnvs.Clear
>end sub
>
>
>'inline
>Set cnvs = Display.Canvas
>cnvs.text Display.XRes, Display.YRes, "Hello, World!"
>
>sleep(500)
>Call clearcanvas("cnvs")
>
>cnvs.text Display.XRes, Display.YRes, "Hello, Sam!"
>sleep(500)
>
>*****
>
>Now obviously, I can't use "cnvs" like that, but it's a great way In 
>this example, what I want to do is use the contents of the string 
>namecnvs to represent the name of any canvas I desire, but I don't 
>know how.  When using namecnvs as is, e-prime would treat it as 
>another slide.  I can't find anything in e-prime that would allow me 
>to either identify something as a variable (like a $ in bash) or use 
>it's contents dynamically. I can do this in bash and matlab, and in 
>C, but I can't figure out how to do this in E-Prime.  I could do 
>some really neat things (I find scripting to be neat) if I could 
>just nail this issue.
>
>Thank you for your time, and happy holidays!

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