OpenEuphoria

RE: Help creating procedures

• Posted by Derek Parnell <ddparnell at bigpond.com> Jul 19, 2001
• 339 views

Hi David,

> From: dstanger at belco.bc.ca
> To: EUforum <EUforum at topica.com>
> Reply-To: EUforum at topica.com
> Subject: Help creating procedures
> Date: 20/07/2001 4:11:43 AM
> 
 
> I am writng a program in DOS32 that displays bitmaps a lot and I am
> attempting to write two procedures that will make this task 
> easier to code.
> My first procedure allows me to load a bitmap and display it 
> at a certain
> point on screen with one line of code:
> 
> procedure image(sequence name, integer x, integer y)
> 
> integer error
> object bitmap
> 
> bitmap = read_bitmap(name & ".bmp")
> error = sequence(bitmap)
> 
> if error = 0 then
>     puts(1, "Error loading bitmap")
>     abort(0)
> else
>     all_palette(bitmap[1] / 4)
>     bitmap = bitmap[2]
>     display_image({x,y}, bitmap)
> end if
> 
> end procedure
> 
> Now I can call a bitmap and display it like so:
> image("c:\\euphoria\\bitmaps\\test", 100, 100)
> 
> What I want to do now it have another procedure called 
> address that would
> allow me to list the address seperately and have image() use 
> that each time
> so that I do not have to type it repeatedly. Something like:
> 
> procedure address(sequence where_is_it)
> end procedure
> 
> Used like so:
> 
> address("c:\\euphoria\\bitmaps\\")
> 
> My problem is that when I try to place where_is_it in 
> procedure image() I am
> informed that where_is_it has not been declared. I have been 
> trying all
> sorts of things but nothing solves the problem. This error is 
> resulting
> before the program even runs.

I suspect that the problem is that the "address" procedure has been defined
after the "image" procedure. Euphoria is a bit simplistic in this regard,
unlike some other languages. Euphoria can only use routines if it has
already seen their definition earlier in the source code. 

Thus ...
  procedure aa()
  end procedure

  procedure bb()
     aa()
  end procedure

is okay but ...

  procedure bb()
     aa()
  end procedure

  procedure aa()
  end procedure

is not okay. You may have to manually rearrange your source code so that
Euphoria stops complaining.

-----------
cheers,
Derek Parnell
Senior Design Engineer
Global Technology Australasia Ltd
dparnell at glotec.com.au

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