Elisp ido mode with history for a list fo symbols

Question

I have a finite list of symbols and I want to make an ido based user interface to select among them, but i also want this to be able to remember. What I came up with is this:

(defvar hist nil)
(ido-completing-read "What, ... is your favorite color? " '("red" "green" "blue") nil t nil 'hist)

But no matter how many times i choose green the colors seem to come up in the same order and hist remains nil. Can anyone help?

Answer 1

Elisp uses dynamic scoping, which means that variable names really matter. More specifically, in your case you have a naming conflict between your hist and the hist variable used by ido. Always use a <prefix>- thingy on global variables to avoid such problems.