Re: How to shadow a function temporarily? (flet and cl-flet)

[Barry Margolin]

In article <mailman.12843.1390745495.10748.help-gnu-emacs@gnu.org>,
 Alex Kost <alezost@gmail.com> wrote:

> Hello, I have 2 questions.
> 
> 1. The main question is: how can I override a function with another
> compatible function (with the same args) temporarily?
> 
> I want something like this:
> 
> (let-shadow ((+ '-))
>   (+ 3 2))  ; should return 1, not 5
> 
> 2. If there is no such macro, I can use `flet' for my purposes, but it
> is obsolete and `cl-flet' doesn't do what I need (see attached example).
> 
> According to (info "(cl) Obsolete Macros"), `flet' makes a dynamic
> binding (unlike `cl-flet').  So the second question is: how can I avoid
> using obsolete `flet` if I need a dynamic binding?

Use `letf' of `symbol-function':

(letf ((symbol-function 'function-name) (symbol-function 
'other-function))
  ...)

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***