Check if drawing is open

I have a lisp that will open an x-ref. What happens is the person will pick the x-ref, then it will open and make it current. All works perfect, except if the drawing is open by someone else. If you have it open, it just switches to make it the current drawing in AutoCAD. I have seen some answers, but they require other programs. I was hoping that this could be done with just the tools AutoCAD gives, ie. lisp vlisp ActiveX.

Any help is appreciated.
Tim

 

Here's a quick 'n dirty method.....returns T if a drawing is open, nil
otherwise

(defun fileopen? (fname / temp)
(if (setq temp (open fname "a"))
(progn ;it's appendable so it's not open
(close temp)
nil
)
(progn ;else it's read only so it's open
t
)
)
)

 

Jeff,

Thanks, I looked at that, and tried (open "filename" "w") and almost lost my work. Didn't think to try it with "a". Oh well, alls well that ends well, and this one ended well.

Tim