Re: [PATCH RFC3.5 08/12] send-email: Move Subject sanitization from --compose code to send_message

[Michael Witten <mfwitten@gmail.com>]

On Sun, Apr 19, 2009 at 09:39, Michael Witten <mfwitten@gmail.com> wrote:
> I'm morally opposed to this kind of thing. The caller should be
> required to test whether quote_rfc2047() is required, as it's not the
> job of quote_rfc2047 to validate. Suppose that quote_rfc2047 were
> actually part of a library of useful functions that my program
> imports. Perhaps my program knows that it must always quote some piece
> of text. Why, then, should my program be forced to waste the cycles to
> perform a useless test?
>
> IMnsHO, verification should always be done by the caller with one
> exception: Interactive (human) input should always be verified,
> because humans represent an unreliable component in the system (in
> terms of digital systems, their asynchronous input must be
> synchronized with the clocked system). WIth this model, there's are
> fewer wasted cycles, because you can reuse verification across similar
> functions, and the code (particularly library code) is easier to
> understand.

I should add, though, that making the logic of the program clear is a
good idea. In that sense, your approach makes sense. Since we 'own'
quote_rfc2047(), I'd say we could take your approach, but rename the
function to something like quote_rfc2047_if_necessary(). If
quote_rfc2047() were part of a library, I think the only moral
solution would be to insist that callers wrap it in another function
named quote_rfc2047_if_necessary().