Arc Forum | > Assigning to local variables using '=' does not create new global variable...

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1 point by i4cu 2131 days ago | link | parent

> Assigning to local variables using '=' does not create new global variables.

We're referring to the original posts problem where using = inside a function can redefine global variables:

  arc> (= data* '(green red)) 

  arc> (def my-fn () (= data* nil))
  #<procedure: my-fn>
  arc> (my-fn)
  nil
  arc> data*
  nil

Now my comment was referring a bigger problem that falls out of this 'feature' or 'anti-feature' (depending on your point of view).

assume you place this in html.arc

  (= data* '(blue red))

  ; (add-color 'purple)
  (def add-color (color)
    (push color data*))

Then I create apple tracker library 'lib/apples.arc' with:

  (= data* '(green red))

  ; (add-apple 'golden)
  (def add-apple (color)
    (push color data*))

Now at the top level of my progam:

  (load "lib/apples.arc")
  (load "lib/html.arc")

; now say the first apple in storage has gone brown:

  > (string (car data*) " has gone brown")

  "blue has gone brown"

say what? my blue apple has gone brown?

why is there no warning or error on loading my lib? That's pretty bad IMO.