Basic question about autoload function

Basic question about autoload function

[Kaushal Modi]

Hello,

I have recently realized that

  (autoload #'foo-fn "bar-pkg")

works even if foo-fn is *not* defined inside bar-pkg. The documentation
also doesn't say that it has to be that way.

So I was just pleasantly surprised that that did the right thing. I looked
at src/eval.c to confirm if that was the case (that it didn't matter if
foo-fn was or wasn't inside bar-pkg).. but I don't understand what's going
on in there (don't understand C).

Can someone confirm?
-- 

Kaushal Modi

RE: Basic question about autoload function

[Drew Adams]

> I have recently realized that (autoload #'foo-fn "bar-pkg")
> works even if foo-fn is *not* defined inside bar-pkg.

What do you mean by "works"?

All that does is cause file bar-pkg.el[c] to be loaded
whenever someone or something tries to invoke/use function,
macro, or keymap `foo-fn'.  (But it does nothing if `foo-fn'
is a function already defined.)

Yes, nothing implies that `foo-fn' is defined in bar-pkg.el.

> The documentation also doesn't say that it has to be that way.

What doesn't have to be what way?

> So I was just pleasantly surprised that that did the right thing.

The right thing being ___?  I guess you wanted Emacs to
load that file when that function is invoked?

Re: Basic question about autoload function

[Kaushal Modi]

On Wed, Dec 6, 2017 at 2:04 PM Drew Adams <drew.adams@oracle.com> wrote:

> > I have recently realized that (autoload #'foo-fn "bar-pkg")
> > works even if foo-fn is *not* defined inside bar-pkg.
>
> What do you mean by "works"?
>

By "works", I meant that bar-pkg got loaded when I called foo-fn. Sorry, I
myself hate the "works" and "does not work" phrases and I ended up using
those.

All that does is cause file bar-pkg.el[c] to be loaded
> whenever someone or something tries to invoke/use function,
> macro, or keymap `foo-fn'.  (But it does nothing if `foo-fn'
> is a function already defined.)
>
> Yes, nothing implies that `foo-fn' is defined in bar-pkg.el.
>

Thanks.

> The documentation also doesn't say that it has to be that way.
>
> What doesn't have to be what way?
>

I meant to say that the documentation does not imply that the FUNCTION has
to be defined inside FILE. I was wondering if that was intentional i.e.
FUNCTION can or cannot be defined inside FILE.

> So I was just pleasantly surprised that that did the right thing.
>
> The right thing being ___?  I guess you wanted Emacs to
> load that file when that function is invoked?
>

Yes, bar-pkg got loaded even when I called foo-fn (where foo-fn was defined
outside bar-pkg).. no errors, nothing.. it just worked as I thought.
-- 

Kaushal Modi

Re: Basic question about autoload function

[Michael Heerdegen]

Kaushal Modi <kaushal.modi@gmail.com> writes:

> I meant to say that the documentation does not imply that the FUNCTION
> has to be defined inside FILE. I was wondering if that was intentional
> i.e.  FUNCTION can or cannot be defined inside FILE.

Looking at the DEFUN of `autoload-do-load' in eval.c, it is only checked
whether after loading the FILE, the `indirect-function' of the symbol
FUNCTION has changed.  So AFAICT yes, it doesn't matter where the
function is defined, as long as it has been defined after loading the
FILE.  Which is also what I would expect, since "the file which defined
some function" is not necessarily well-defined.


Michael.

Re: Basic question about autoload function

[Kaushal Modi]

On Fri, Dec 8, 2017 at 8:39 AM Michael Heerdegen <michael_heerdegen@web.de>
wrote:

> Looking at the DEFUN of `autoload-do-load' in eval.c, it is only checked
> whether after loading the FILE, the `indirect-function' of the symbol
> FUNCTION has changed.  So AFAICT yes, it doesn't matter where the
> function is defined, as long as it has been defined after loading the
> FILE.  Which is also what I would expect, since "the file which defined
> some function" is not necessarily well-defined.
>

Thank you.
-- 

Kaushal Modi