AutoLisp getpoint and echo test (CorelCAD viability investigation.)

getpoint-echo-test.lsp

;| Set Variable |;
(setq p1 (getpoint))
;| CorelCAD Output |;
; (73.0 9.65125 0.0)

;| Point is interpretted as a bad function. It's a list with no command. |;
(p1)
;| CorelCAD Output |;
; Error: Invalid parameter.

;| Wrapping in a list helps, but is dirty |;
(list p1)
;| CorelCAD Output |;
; ((73.0 9.65125 0.0))

;| FlatMap into new list is clean. |;
(append p1)
;| CorelCAD Output |;
; (73.0 9.65125 0.0)

;| Use `eval` for indirect invocation. Probably cleanes syntax. |;
(eval 'p1) 
;| CorelCAD Output |;
; (73.0 9.65125 0.0)

;| Use `progn` to evaluate and echo return value (last list item). Creates anonymous function block. |;
(progn (setq p1 (getpoint)) p1)
;| CorelCAD Output |;
; (47.88 25.39270337 0.0)

;| Akward Output from print functions |;
(print p1)
;| CorelCAD Output |;
; (73.0 9.65125 0.0) (73.0 9.65125 0.0)
; Why does this duplicate in Corel CAD? All prin{1,n,c} functions do this.

I have CorelCAD 2019 and wanted to try AutoLisp and see how compatible it was with online tutorials for AutoCad.

My target application would need to collect points, so I wanted to start with collecting and echoing the points.

I did not realize the echoing was going to be the hard part.

I was a complete AutoLisp newcomer, with no experience in a real Autocad environment. It took me a while to establish that the point was being saved in a global scope. This was because all methods I tried to echo the point were leading to it being evaluated improperly as a function call, or using incompatible features and commands.

Once I was able to get the coordinates printed, I worked my way backwards to a cleaner process and started to document my options.

This is the result of that session.