Re: How does letf work?

[Emanuel Berg]

Florian Beck <fb@miszellen.de> writes:

> The docstring of letf says: "This is the analogue of
> let', but with generalized variables (in the sense of
> setf') for the PLACEs."

(letf (((cdr test-x) '(a b c d)))
  (message "%s" test-x) ; says '(KEY a b c d)
  (cdr test-x) )        ; => (a b c d)

(And `... (nth 1 test-x)' => 'a, and so on.)

But:

(letf (((cdr test-x) '(a b c d)))
  (message "%s" test-x) ; says '(KEY a b c d)
  test-x)               ;   => '(KEY 1 2 3 4)

`letf' (or `cl-letf') resets the values when it exits:

> On exit, either normally or because of a `throw' or
> error, the PLACEs are set back to their original
> values.

So perhaps this inconsistency is due to the
implementation of that.

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