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Sun, 06 Oct 2013 17:35:30 +0800
Gnus/5.130008 (Ma Gnus v0.8) Emacs/24.3 (gnu/linux)
I've got a variable binding scenario that I thought would be easy to
resolve, but is giving me trouble. I have the feeling that this scenario
represents some sort of Lesson 1 in How Bindings Work, but I'm still not
sure of the proper solution.
The general situation is: I want to start with a list template stored in
a variable. Another function in this library starts with the template,
modifies it a few times, then does something with the modified version.
Every time this function is called, it should start with a "fresh" copy
of the template.
Clearly the following doesn't work: it actually modifies the original
'(item ((with . "some")
(sub . "lists"))
nil (other things will go here)))
(defun main-entry-function ()
;; obviously this doesn't work as defvars are always special
(let ((list-template list-template))
;; list-template is accessed dynamically in the following functions
The other option would be to pass list-template as an argument to each
of these functions. I guess each call would then have to look like:
(setq list-template (modify-list-template list-template))
This seems ugly, and it won't necessarily be easy to ensure the
modifying functions end by returning the new value of list-template.
What's the best way of handling this? And is there one "right" solution
for both dynamic and lexical binding?
PS: The wiki mentions pretty much exactly my scenario, but doesn't
actually say what should be done.
- binding question,
Eric Abrahamsen <=