Re: Passing optional arguments for use with internal functions

[Emanuel Berg]

Heime wrote:

>> Optional arguments defaults to nil, if that is an
>> acceptable value you can use it as you do, if not you can
>> check if it is nil first thing in the function and if it
>> is, set it to something that works, e.g.
>> 
>> (or arg (setq arg 0))
>
> Does the condition you specified work whether the binding is
> lexical or dynamic ?

If there is an optional argument with that name yes, since
formal parameters (function arguments) are always lexical.

;;; -*- lexical-binding: nil -*-

(defvar arg)
(setq arg 2)

(defun echo-arg (&optional arg)
  (or arg (setq arg 1))
  (message "%s" arg) )

;; (echo-arg)

This will still echo 1.

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