Re: insert-header-preprocessor-definition

[Emanuel Berg]

Ben Bacarisse wrote:

> That is safe, yes. Doing it by hand, I think
> most people write H_COLOR [...] Actually,
> I like the symmetry

I like symmetry too but not for symmetry's
sake, so I removed the part that transformed
".h" into "_H" - which, ironically, I didn't
put there for the symmetry! Anyway now it is
just H_COLOR. [1]

Also, altho I've thought about this on and off
since I heard of it, I have failed to come to
terms with the underlying issue. How can
COLOR_H lead to an error when H_COLOR (or
H_COLOR_H) doesn't?

Because the syntax is the same, and all letters
are plain ASCII (the 2^7 table, where "_", the
underscore or "unit separator", is at number 95
counting from 0; see ascii(7)).

So there must be some fishy semantics going on.
Perhaps one needs to do a special study of the
C preprocessor? And if so, are there other
conventions one should be aware of?

And just what kind of error is it we're
trying (succeeding) to avoid?

[1] http://user.it.uu.se/~embe8573/emacs-init/ide/c-and-cpp.el

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