Re: about "assignment to free variable"

[Stefan Monnier]

> Ok, thanks! so, it was not necessary to assign the return value of
> read-from-minibuffer to backend, because it assigns already the first
> element.
> wright?

More or less.  It doesn't really "assign" it.  Instead it takes the list
constructed by the EXP in (interactive EXP) and calls the function with
it, as if you had written (apply FUNCTION EXP).


        Stefan