Re: Partial wdired (edit just filename at the point)

[Stefan Monnier]

>    ELISP> (eval (byte-compile '(type-of #'(lambda () 42))))
>    compiled-function
>
>> And FWIW, I'd like to get to the point where (type-of (lambda () 42))
>> never returns `cons` but always some kind of "function" type instead,
>> indeed.
>
> Do you mean more like the Common Lisp behaviour?
>
> Getting back to the original advice, in compiled code or in such `some
> kind of "function"' future, using #' will make it not possible to
> redefine wdired--preprocess-line in the hook:

No, I was talking about #'(lambda...) not about #'<symbol>.
IOW, I was talking about having `lambda` returning an actual function
object instead of returning a "list that can be treated as a function".

The use of #'<symbol> to refer to the actual symbol (so that it will
change its semantics whenever that symbol's definition is changed) is
much too ingrained in ELisp, I think changing it would introduce a lot
of breakage and I'm not sure what the benefit would be: there's already
`symbol-function` for that.

> I would like to understand when to prefer #' and when '.

Use #' when you refer to a function by name, use ' when you're just
referring to the symbol for some other reason (it might be a face,
a variable's name, some arbitrary constant, ...).

My rule of thumb is to write #'<foo> whenever I could also place here the
content of (symbol-function 'foo), just with a slightly different semantics.

For example, I prefer to write

    (defalias 'foo #'bar)

because it does something quite similar to

    (defalias 'foo (symbol-function 'bar))

whereas it does something very different from

    (defalias (symbol-function 'foo) #'bar)


-- Stefan