Re: Declaring a local dynamic variable?

[Barry Margolin]

In article <mailman.2622.1379742443.10748.help-gnu-emacs@gnu.org>,
 Andreas Röhler <andreas.roehler@easy-emacs.de> wrote:

> Am 20.09.2013 22:59, schrieb Barry Margolin:
> > In article <mailman.2578.1379694764.10748.help-gnu-emacs@gnu.org>,
> >   Andreas Röhler <andreas.roehler@easy-emacs.de> wrote:
> >
> >> Am 20.09.2013 17:10, schrieb Barry Margolin:
> >>> In article <mailman.2569.1379688787.10748.help-gnu-emacs@gnu.org>,
> >>>    Andreas Röhler <andreas.roehler@easy-emacs.de> wrote:
> >>>
> >>>> Am 20.09.2013 14:30, schrieb Stefan Monnier:
> >>>>>> If I purposefully use a local dynamic variable as in:
> >>>>>
> >>>>> Use (defvar my-counter) at the file's top-level to indicate that this
> >>>>> variable is used in a way that relies on dynamic scoping.
> >>>>
> >>>> A need to write code just to silence compiler warnings?
> >>>> Emacs could do better.
> >>>
> >>> Other than "code", what would you suggest?
> >>
> >> In the precise case: just drop that warning.
> >>
> >> In a wider sense, IMO a modular approach is better.
> >> Restrict compiler warnings to obvious errors, don't mix style questions in.
> >
> > This isn't a style warning. Often the reason is mistyping a local
> > variable name.
> >
> > (let ((foobar ...))
> >     ...
> >     (blah fobar)
> >     ...)
> >
> 
> This is another case. IIUC there was nothing wrong with the OP's example.

But how is the compiler supposed to know the difference? Either it 
always warns, and generate false positives when you compile the user of 
a variable before loading the defvar, or never warns and there are false 
negatives when the user makes a typo.

In this case, false positives are the better option, since you can 
easily silence them by adding a defvar. If the warning were removed, 
there's no way to get the warning when you actually do make a typo.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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