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Re: dynamic and lexical scope, attempted summary with example


From: Emanuel Berg
Subject: Re: dynamic and lexical scope, attempted summary with example
Date: Tue, 22 Jul 2014 00:11:46 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)

Thien-Thi Nguyen <address@hidden> writes:

> I would make sure A and B are always strings and use
> ‘concat’.  For filenames, i would use
> ‘(expand-file-name B A)’.

Do you suggest this because "you should always verify
the input"? With `stringp', in this case?

If you verify all inputs as a matter of principle I
guess `file-exists-p' should be put somewhere as well?

And: `expand-file-name' - because it is more
portable/safe, replacing tilde with the literal
/home/user/ and possibly other housekeeping?

Well, all those considerations aren't really an issue
as the only person using this will be yours truly and
all possible bugs will be found instantly (and without
harm) and corrected. `expand-file-name' I'll use as a
matter of principle but verifying indata, for all
zillion defuns it would be lots of work for catching
accidental maluse of the software - does that usually
pay off? In my experience, I don't think so.

> If i answer "no", then both of us may be fooling
> ourselves, but in a safe way.  If i answer "yes",
> then there is only one fool (me), but the foolishness
> i am capable of is huge.
>
> The result of the _insertion_ of literal values at
> the places of the parameters, will result in a
> function that don't use variables (dynamic or
> lexical) but _hard-coded_ values - that issue is
> _eliminated_.
>
> Do you think it is correct in terms of technology?
>
> Mu!  (See above.)  Actually, i'd add "places" and
> "will result" to my list of confusions.

I know you understand because you have read the code
which you understand instantly. Of course English
cannot describe the code perfectly, but I bet it didn't
add to your confusion. If you know a better way to
describe it do tell.

-- 
underground experts united


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