Re: Trouble with lexical-binding.

[Stefan Monnier]

> I don't think it can break code defined elsewhere : the (defvar ptr)
> form only has effect in its lexical scope, unlike the 2+ arguments
> versions where a default value is provided.

Indeed, these (defvar <shortvar>) are sufficiently common that I had to
make sure that they don't wreak havoc too often, so such `defvar' try
their best to only affect the current scope (typically: the current
file).

But if you have a file foo.el with

   ;;; - lexical-binding:t -*-
   (defun foo (x)
     (let ((ptr x))
       (lambda (y) (+ ptr y))))

and a file bar.el with

   ;;; - lexical-binding:t -*-
   (defvar ptr)
   (defun bar ()
     (let* ((ptr 6)
            (f (foo 3)))
       (message "%S" (funcall f 1))))

Then

    emacs -Q --batch -l ~/tmp/foo.elc -l ~/tmp/bar.el --eval '(bar)'
and
    emacs -Q --batch -l ~/tmp/foo.el -l ~/tmp/bar.el --eval '(bar)'

won't give you the same answer :-(


        Stefan