* reference variable before definition
@ 2017-03-12 2:03 Eric Abrahamsen
2017-03-12 2:06 ` Eric Abrahamsen
2017-03-12 3:18 ` Stefan Monnier
0 siblings, 2 replies; 6+ messages in thread
From: Eric Abrahamsen @ 2017-03-12 2:03 UTC (permalink / raw)
To: help-gnu-emacs
I can't tell if it's always been this way: I'm getting compiler warnings
about "reference to free variable" if the variable appears in a function
definition before it's defined in the file. So compiling this produces
warnings:
(defun make-my-day ()
(message "It's: %s" my-day))
(defvar my-day "Monday")
Has it always been this way, and it only just got through to me? I
didn't think it was necessary to define everything before use in a
function...
Hoping I'm just hallucinating something,
Eric
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: reference variable before definition
2017-03-12 2:03 reference variable before definition Eric Abrahamsen
@ 2017-03-12 2:06 ` Eric Abrahamsen
2017-03-12 3:18 ` Stefan Monnier
1 sibling, 0 replies; 6+ messages in thread
From: Eric Abrahamsen @ 2017-03-12 2:06 UTC (permalink / raw)
To: help-gnu-emacs
Eric Abrahamsen <eric@ericabrahamsen.net> writes:
[...]
> Hoping I'm just hallucinating something,
It just occurred to me, I might be seeing the difference between "B" in
dired and `batch-byte-compile' on the command line...
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: reference variable before definition
2017-03-12 2:03 reference variable before definition Eric Abrahamsen
2017-03-12 2:06 ` Eric Abrahamsen
@ 2017-03-12 3:18 ` Stefan Monnier
2017-03-12 3:40 ` Eric Abrahamsen
1 sibling, 1 reply; 6+ messages in thread
From: Stefan Monnier @ 2017-03-12 3:18 UTC (permalink / raw)
To: help-gnu-emacs
> Has it always been this way, and it only just got through to me? I
> didn't think it was necessary to define everything before use in a
> function...
I think it's been that way for a while, yes. It used not to be terribly
important, indeed, but since Emacs-24 it became a lot more important,
because the byte-compiler compiles variables differently if they've been
declared via `defvar`. And it doesn't first scan the buffer for
defvars, so by the time it sees the defvar it has already (mis)compiled
the earlier uses of that variable.
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: reference variable before definition
2017-03-12 3:18 ` Stefan Monnier
@ 2017-03-12 3:40 ` Eric Abrahamsen
2017-03-12 3:55 ` Stefan Monnier
0 siblings, 1 reply; 6+ messages in thread
From: Eric Abrahamsen @ 2017-03-12 3:40 UTC (permalink / raw)
To: help-gnu-emacs
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> Has it always been this way, and it only just got through to me? I
>> didn't think it was necessary to define everything before use in a
>> function...
>
> I think it's been that way for a while, yes. It used not to be terribly
> important, indeed, but since Emacs-24 it became a lot more important,
> because the byte-compiler compiles variables differently if they've been
> declared via `defvar`. And it doesn't first scan the buffer for
> defvars, so by the time it sees the defvar it has already (mis)compiled
> the earlier uses of that variable.
Okay. Apparently this also applies to defclasses and slot access -- the
classes need to be defined before any function calls slot-value. I'm
surprised I never ran into this before...
Off to churn some code,
Eric
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: reference variable before definition
2017-03-12 3:40 ` Eric Abrahamsen
@ 2017-03-12 3:55 ` Stefan Monnier
2017-03-12 7:26 ` Eric Abrahamsen
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Monnier @ 2017-03-12 3:55 UTC (permalink / raw)
To: help-gnu-emacs
> Okay. Apparently this also applies to defclasses and slot access -- the
> classes need to be defined before any function calls slot-value. I'm
> surprised I never ran into this before...
This one *is* new, tho. And it's really just a warning to help catch
typos (and cases where init-args are misused for slot names): it doesn't
have any actual effect.
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: reference variable before definition
2017-03-12 3:55 ` Stefan Monnier
@ 2017-03-12 7:26 ` Eric Abrahamsen
0 siblings, 0 replies; 6+ messages in thread
From: Eric Abrahamsen @ 2017-03-12 7:26 UTC (permalink / raw)
To: help-gnu-emacs
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> Okay. Apparently this also applies to defclasses and slot access -- the
>> classes need to be defined before any function calls slot-value. I'm
>> surprised I never ran into this before...
>
> This one *is* new, tho. And it's really just a warning to help catch
> typos (and cases where init-args are misused for slot names): it doesn't
> have any actual effect.
Good to know. But some of us are compulsive about hygiene!
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-03-12 7:26 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2017-03-12 2:03 reference variable before definition Eric Abrahamsen
2017-03-12 2:06 ` Eric Abrahamsen
2017-03-12 3:18 ` Stefan Monnier
2017-03-12 3:40 ` Eric Abrahamsen
2017-03-12 3:55 ` Stefan Monnier
2017-03-12 7:26 ` Eric Abrahamsen
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